A 37-amino acid residue peptide isolated from the scorpion Leiurus quinquestriatus hebraeus. It is a neurotoxin that inhibits calcium activated potassium channels.
Venoms from animals of the order Scorpionida of the class Arachnida. They contain neuro- and hemotoxins, enzymes, and various other factors that may release acetylcholine and catecholamines from nerve endings. Of the several protein toxins that have been characterized, most are immunogenic.
A highly neurotoxic polypeptide from the venom of the honey bee (Apis mellifera). It consists of 18 amino acids with two disulfide bridges and causes hyperexcitability resulting in convulsions and respiratory paralysis.
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.
Endogenously-synthesized compounds that influence biological processes not otherwise classified under ENZYMES; HORMONES or HORMONE ANTAGONISTS.
Potassium channels whose activation is dependent on intracellular calcium concentrations.
A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)
One of the POTASSIUM CHANNEL BLOCKERS, with secondary effect on calcium currents, which is used mainly as a research tool and to characterize channel subtypes.
A major class of calcium-activated potassium channels that were originally discovered in ERYTHROCYTES. They are found primarily in non-excitable CELLS and set up electrical gradients for PASSIVE ION TRANSPORT.
An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide.
The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
A major class of calcium activated potassium channels whose members are voltage-dependent. MaxiK channels are activated by either membrane depolarization or an increase in intracellular Ca(2+). They are key regulators of calcium and electrical signaling in a variety of tissues.
That phase of a muscle twitch during which a muscle returns to a resting position.
Arteries which arise from the abdominal aorta and distribute to most of the intestines.
An imidazole derivative with a broad spectrum of antimycotic activity. It inhibits biosynthesis of the sterol ergostol, an important component of fungal CELL MEMBRANES. Its action leads to increased membrane permeability and apparent disruption of enzyme systems bound to the membrane.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
Drugs used to cause dilation of the blood vessels.
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
Inorganic compounds that contain barium as an integral part of the molecule.
Arthropods of the order Scorpiones, of which 1500 to 2000 species have been described. The most common live in tropical or subtropical areas. They are nocturnal and feed principally on insects and other arthropods. They are large arachnids but do not attack man spontaneously. They have a venomous sting. Their medical significance varies considerably and is dependent on their habits and venom potency rather than on their size. At most, the sting is equivalent to that of a hornet but certain species possess a highly toxic venom potentially fatal to humans. (From Dorland, 27th ed; Smith, Insects and Other Arthropods of Medical Importance, 1973, p417; Barnes, Invertebrate Zoology, 5th ed, p503)
An inhibitor of nitric oxide synthetase which has been shown to prevent glutamate toxicity. Nitroarginine has been experimentally tested for its ability to prevent ammonia toxicity and ammonia-induced alterations in brain energy and ammonia metabolites. (Neurochem Res 1995:200(4):451-6)
Tetraethylammonium compounds refer to a group of organic salts containing the tetraethylammonium ion (N(C2H5)4+), which is characterized by four ethyl groups bonded to a central nitrogen atom, and are commonly used in research and medicine as pharmacological tools for studying ion channels.
A delayed rectifier subtype of shaker potassium channels that is the predominant VOLTAGE-GATED POTASSIUM CHANNEL of T-LYMPHOCYTES.
Paracrine substances produced by the VASCULAR ENDOTHELIUM with VASCULAR SMOOTH MUSCLE relaxation (VASODILATION) activities. Several factors have been identified, including NITRIC OXIDE and PROSTACYCLIN.
A potassium-channel opening vasodilator that has been investigated in the management of hypertension. It has also been tried in patients with asthma. (Martindale, The Extra Pharmacopoeia, 30th ed, p352)
Venoms from snakes of the family Elapidae, including cobras, kraits, mambas, coral, tiger, and Australian snakes. The venoms contain polypeptide toxins of various kinds, cytolytic, hemolytic, and neurotoxic factors, but fewer enzymes than viper or crotalid venoms. Many of the toxins have been characterized.
Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system. Most venoms contain neurotoxic substances. Myotoxins are included in this concept.
Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.
A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.
A group of compounds that are monomethyl derivatives of pyridines. (From Dorland, 28th ed)
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
The nonstriated involuntary muscle tissue of blood vessels.
The pore-forming subunits of large-conductance calcium-activated potassium channels. They form tetramers in CELL MEMBRANES.
A major class of calcium-activated potassium channels that are found primarily in excitable CELLS. They play important roles in the transmission of ACTION POTENTIALS and generate a long-lasting hyperpolarization known as the slow afterhyperpolarization.
A non-steroidal anti-inflammatory agent (NSAID) that inhibits the enzyme cyclooxygenase necessary for the formation of prostaglandins and other autacoids. It also inhibits the motility of polymorphonuclear leukocytes.
A non-selective inhibitor of nitric oxide synthase. It has been used experimentally to induce hypertension.
A morpholinyl sydnone imine ethyl ester, having a nitrogen in place of the keto oxygen. It acts as NITRIC OXIDE DONORS and is a vasodilator that has been used in ANGINA PECTORIS.
Potassium channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. The opening of these channels is induced by the membrane depolarization of the ACTION POTENTIAL.
Oxadiazoles are heterocyclic organic compounds consisting of a five-membered ring containing two carbon atoms, one nitrogen atom, and two oxygen atoms (one as a part of the oxadiazole ring and the other as a substituent or part of a larger molecule), which can exist in various isomeric forms and are known for their versatile biological activities, including anti-inflammatory, antiviral, antibacterial, and antitumor properties.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The regulatory subunits of large-conductance calcium-activated potassium channels.
The relationship between the dose of an administered drug and the response of the organism to the drug.
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
Voltage-gated potassium channels whose primary subunits contain six transmembrane segments and form tetramers to create a pore with a voltage sensor. They are related to their founding member, shaker protein, Drosophila.
The ability of a substrate to allow the passage of ELECTRONS.
Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)
A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.
A nonapeptide messenger that is enzymatically produced from KALLIDIN in the blood where it is a potent but short-lived agent of arteriolar dilation and increased capillary permeability. Bradykinin is also released from MAST CELLS during asthma attacks, from gut walls as a gastrointestinal vasodilator, from damaged tissues as a pain signal, and may be a neurotransmitter.
An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.
A stable prostaglandin endoperoxide analog which serves as a thromboxane mimetic. Its actions include mimicking the hydro-osmotic effect of VASOPRESSIN and activation of TYPE C PHOSPHOLIPASES. (From J Pharmacol Exp Ther 1983;224(1): 108-117; Biochem J 1984;222(1):103-110)
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
A class of drugs that act by selective inhibition of calcium influx through cellular membranes.
Agents that increase calcium influx into calcium channels of excitable tissues. This causes vasoconstriction in VASCULAR SMOOTH MUSCLE and/or CARDIAC MUSCLE cells as well as stimulation of insulin release from pancreatic islets. Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders. They have been used primarily in experimental studies in cell and tissue culture.
An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE.
Compounds with a core of fused benzo-pyran rings.
A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.
Quinoxalines are heterocyclic organic compounds consisting of a benzene fused to a pyrazine ring, which have been studied for their potential antibacterial, antifungal, and anticancer properties.
The smallest divisions of the arteries located between the muscular arteries and the capillaries.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.
A group of slow opening and closing voltage-gated potassium channels. Because of their delayed activation kinetics they play an important role in controlling ACTION POTENTIAL duration.
A large vessel supplying the whole length of the small intestine except the superior part of the duodenum. It also supplies the cecum and the ascending part of the colon and about half the transverse part of the colon. It arises from the anterior surface of the aorta below the celiac artery at the level of the first lumbar vertebra.
Guanosine cyclic 3',5'-(hydrogen phosphate). A guanine nucleotide containing one phosphate group which is esterified to the sugar moiety in both the 3'- and 5'-positions. It is a cellular regulatory agent and has been described as a second messenger. Its levels increase in response to a variety of hormones, including acetylcholine, insulin, and oxytocin and it has been found to activate specific protein kinases. (From Merck Index, 11th ed)
A guanidine that opens POTASSIUM CHANNELS producing direct peripheral vasodilatation of the ARTERIOLES. It reduces BLOOD PRESSURE and peripheral resistance and produces fluid retention. (Martindale The Extra Pharmacopoeia, 31st ed)
A 20-carbon-chain fatty acid, unsaturated at positions 8, 11, and 14. It differs from arachidonic acid, 5,8,11,14-eicosatetraenoic acid, only at position 5.
An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.
Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates.
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
Compounds or agents that combine with cyclooxygenase (PROSTAGLANDIN-ENDOPEROXIDE SYNTHASES) and thereby prevent its substrate-enzyme combination with arachidonic acid and the formation of eicosanoids, prostaglandins, and thromboxanes.
Drugs used to cause constriction of the blood vessels.
The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.
Compounds with a BENZENE fused to IMIDAZOLES.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
The veins and arteries of the HEART.

RINm5f cells express inactivating BK channels whereas HIT cells express noninactivating BK channels. (1/460)

Large-conductance Ca2+- and voltage-activated BK-type K+ channels are expressed abundantly in normal rat pancreatic islet cells and in the clonal rat insulinoma tumor (RINm5f) and hamster insulinoma tumor (HIT) beta cell lines. Previous work has suggested that the Ca2+ sensitivity of BK channels in RIN cells is substantially less than that in HIT cells, perhaps contributing to differences between the cell lines in responsiveness to glucose in mediating insulin secretion. In both RIN cells and normal pancreatic beta cells, BK channels are thought to play a limited role in responses of beta cells to secretagogues and in the electrical activity of beta cells. Here we examine in detail the properties of BK channels in RIN and HIT cells using inside-out patches and whole cell recordings. BK channels in RIN cells exhibit rapid inactivation that results in an anomalous steady-state Ca2+ dependence of activation. In contrast, BK channels in HIT cells exhibit the more usual noninactivating behavior. When BK inactivation is taken into account, the Ca2+ and voltage dependence of activation of BK channels in RIN and HIT cells is essentially indistinguishable. The properties of BK channel inactivation in RIN cells are similar to those of inactivating BK channels (termed BKi channels) previously identified in rat chromaffin cells. Inactivation involves multiple, trypsin-sensitive cytosolic domains and exhibits a dependence on Ca2+ and voltage that appears to arise from coupling to channel activation. In addition, the rates of inactivation onset and recovery are similar to that of BKi channels in chromaffin cells. The charybdotoxin (CTX) sensitivity of BKi currents is somewhat less than that of the noninactivating BK variant. Action potential voltage-clamp waveforms indicate that BK current is activated only weakly by Ca2+ influx in RIN cells but more strongly activated in HIT cells even when Ca2+ current magnitude is comparable. Concentrations of CTX sufficient to block BKi current in RIN cells have no effect on action potential activity initiated by glucose or DC injection. Despite its abundant expression in RIN cells, BKi current appears to play little role in action potential activity initiated by glucose or DC injection in RIN cells, but BK current may play an important role in action potential repolarization in HIT cells.  (+info)

Calcium responses induced by acetylcholine in submucosal arterioles of the guinea-pig small intestine. (2/460)

1. Calcium responses induced by brief stimulation with acetylcholine (ACh) were assessed from the fluorescence changes in fura-2 loaded submucosal arterioles of the guinea-pig small intestine. 2. Initially, 1-1.5 h after loading with fura-2 (fresh tissues), ACh increased [Ca2+]i in a concentration-dependent manner. This response diminished with time, and finally disappeared in 2-3 h (old tissues). 3. Ba2+ elevated [Ca2+]i to a similar extent in both fresh and old tissues. ACh further increased the Ba2+-elevated [Ca2+]i in fresh tissues, but reduced it in old tissues. Responses were not affected by either indomethacin or nitroarginine. 4. In fresh mesenteric arteries, mechanical removal of endothelial cells abolished the ACh-induced increase in [Ca2+]i, with no alteration of [Ca2+]i at rest and during elevation with Ba2+. 5. In the presence of indomethacin and nitroarginine, high-K+ solution elevated [Ca2+]i in both fresh and old tissues. Subsequent addition of ACh further increased [Ca2+]i in fresh tissues without changing it in old tissues. 6. Proadifen, an inhibitor of the enzyme cytochrome P450 mono-oxygenase, inhibited the ACh-induced changes in [Ca2+]i in both fresh and Ba2+-stimulated old tissues. It also inhibited the ACh-induced hyperpolarization. 7. In fresh tissues, the ACh-induced Ca2+ response was not changed by apamin, charybdotoxin (CTX), 4-aminopyridine (4-AP) or glibenclamide. In old tissues in which [Ca2+]i had previously been elevated with Ba2+, the ACh-induced Ca2+ response was inhibited by CTX but not by apamin, 4-AP or glibenclamide. 8. It is concluded that in submucosal arterioles, ACh elevates endothelial [Ca2+]i and reduces muscular [Ca2+]i, probably through the hyperpolarization of endothelial or smooth muscle membrane by activating CTX-sensitive K+ channels.  (+info)

Acetylcholine-induced membrane potential changes in endothelial cells of rabbit aortic valve. (3/460)

1. Using a microelectrode technique, acetylcholine (ACh)-induced membrane potential changes were characterized using various types of inhibitors of K+ and Cl- channels in rabbit aortic valve endothelial cells (RAVEC). 2. ACh produced transient then sustained membrane hyperpolarizations. Withdrawal of ACh evoked a transient depolarization. 3. High K+ blocked and low K+ potentiated the two ACh-induced hyperpolarizations. Charybdotoxin (ChTX) attenuated the ACh-induced transient and sustained hyperpolarizations; apamin inhibited only the sustained hyperpolarization. In the combined presence of ChTX and apamin, ACh produced a depolarization. 4. In Ca2+-free solution or in the presence of Co2+ or Ni2+, ACh produced a transient hyperpolarization followed by a depolarization. In BAPTA-AM-treated cells, ACh produced only a depolarization. 5. A low concentration of A23187 attenuated the ACh-induced transient, but not the sustained, hyperpolarization. In the presence of cyclopiazonic acid, the hyperpolarization induced by ACh was maintained after ACh removal; this maintained hyperpolarization was blocked by Co2+. 6. Both NPPB and hypertonic solution inhibited the membrane depolarization seen after ACh washout. Bumetanide also attenuated this depolarization. 7. It is concluded that in RAVEC, ACh produces a two-component hyperpolarization followed by a depolarization. It is suggested that ACh-induced Ca2+ release from the storage sites causes a transient hyperpolarization due to activation of ChTX-sensitive K+ channels and that ACh-activated Ca2+ influx causes a sustained hyperpolarization by activating both ChTX- and apamin-sensitive K+ channels. Both volume-sensitive Cl- channels and the Na+-K+-Cl- cotransporter probably contribute to the ACh-induced depolarization.  (+info)

Differences in the actions of some blockers of the calcium-activated potassium permeability in mammalian red cells. (4/460)

1. The actions of some inhibitors of the Ca2+-activated K+ permeability in mammalian red cells have been compared. 2. Block of the permeability was assessed from the reduction in the net loss of K+ that followed the application of the Ca2+ ionophore A23187 (2 microM) to rabbit red cells suspended at a haematocrit of 1% in a low potassium solution ([K]0 0.12-0.17 mM) at 37 degrees C. Net movement of K+ was measured using a K+-sensitive electrode placed in the suspension. 3. The concentrations (microM +/- s.d.) of the compounds tested causing 50% inhibition of K+ loss were: quinine, 37 +/- 3; cetiedil, 26 +/- 1; the cetiedil congeners UCL 1269, UCL 1274 and UCL 1495, approximately 150, 8.2 +/- 0.1, 0.92 +/- 0.03 respectively; clotrimazole, 1.2 +/- 0.1; nitrendipine, 3.6 +/- 0.5 and charybdotoxin, 0.015 +/- 0.002. 4. The characteristics of the block suggested that compounds could be placed in two groups. For one set (quinine, cetiedil, and the UCL congeners), the concentration-inhibition curves were steeper (Hill coefficient, nH, > or = 2.7) than for the other (clotrimazole, nitrendipine, charybdotoxin) for which nH approximately 1. 5. Compounds in the first set alone became less active on raising the concentration of K+ in the external solution to 5.4 mM. 6. The rate of K+ loss induced by A23187 slowed in the presence of high concentrations of cetiedil and its analogues, suggesting a use-dependent component to the inhibitory action. This was not seen with clotrimazole. 7. The blocking action of the cetiedil analogue UCL 1274 could not be overcome by an increase in external Ca2+ and its potency was unaltered when K+ loss was induced by the application of Pb2+ (10 microM) rather than by A23187. 8. These results, taken with the findings of others, suggest that agents that block the red cell Ca2+-activated K+ permeability can be placed in two groups with different mechanisms of action. The differences can be explained by supposing that clotrimazole and charybdotoxin act at the outer face of the channel whereas cetiedil and its congeners may block within it, either at or near the K+ binding site that determines the flow of K+.  (+info)

Modulation of chloride, potassium and bicarbonate transport by muscarinic receptors in a human adenocarcinoma cell line. (5/460)

1. Short-circuit current (I(SC)) responses to carbachol (CCh) were investigated in Colony 1 epithelia, a subpopulation of the HCA-7 adenocarcinoma cell line. In Krebs-Henseleit (KH) buffer, CCh responses consisted of three I(SC) components: an unusual rapid decrease (the 10 s spike) followed by an upward spike at 30 s and a slower transient increase (the 2 min peak). This response was not potentiated by forskolin; rather, CCh inhibited cyclic AMP-stimulated I(SC). 2. In HCO3- free buffer, the decrease in forskolin-elevated I(SC) after CCh was reduced, although the interactions between CCh and forskolin remained at best additive rather than synergistic. When Cl- anions were replaced by gluconate, both Ca2+- and cyclic AMP-mediated electrogenic responses were significantly inhibited. 3. Basolateral Ba2+ (1-10 mM) and 293B (10 microM) selectively inhibited forskolin stimulation of I(SC), without altering the effects of CCh. Under Ba2+- or 293B-treated conditions, CCh responses were potentiated by pretreatment with forskolin. 4. Basolateral charybdotoxin (50 nM) significantly increased the size of the 10 s spike of CCh responses in both KH and HCO3- free medium, without affecting the 2 min peak. The enhanced 10 s spike was inhibited by prior addition of 5 mM apical Ba2+. Charybdotoxin did not affect forskolin responses. 5. In epithelial layers prestimulated with forskolin, the muscarinic antagonists atropine and 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP, both at 100 nM) abolished subsequent 10 microM CCh responses. Following addition of p-fluoro hexahydro-sila-difenidol (pF-HHSiD, 10 microM) or pirenzepine (1 microM), qualitative changes in the CCh response time-profile also indicated a rightward shift of the agonist concentration-response curve; however, 1 microM gallamine had no effect. These results suggest that a single M3-like receptor subtype mediates the secretory response to CCh. 6. It is concluded that CCh and forskolin activate discrete populations of basolateral K+ channels gated by either Ca2+ or cyclic AMP, but that the Cl- permeability of the apical membrane may limit their combined effects on electrogenic Cl- secretion. In addition, CCh activates a Ba2+-sensitive apical K+ conductance leading to electrogenic K+ transport. Both agents may also modulate HCO3- secretion through a mechanism at least partially dependent on carbonic anhydrase.  (+info)

Mechanical stimulation regulates voltage-gated potassium currents in cardiac microvascular endothelial cells. (6/460)

Vascular endothelial cells are constantly exposed to mechanical forces resulting from blood flow and transmural pressure. The goal of this study was to determine whether mechanical stimulation alters the properties of endothelial voltage-gated K+ channels. Cardiac microvascular endothelial cells (CMECs) were isolated from rat ventricular muscle and cultured on thin sheets of silastic membranes. Membrane currents were measured with the use of the whole-cell arrangement of the patch-clamp technique in endothelial cells subjected to static stretch for 24 hours and compared with measurements from control, nonstretched cells. Voltage steps positive to -30 mV resulted in the activation of a time-dependent, delayed rectifier K+current (IK) in the endothelial cells. Mechanically induced increases of 97%, 355%, and 106% at +30 mV were measured in the peak amplitude of IK in cells stretched for 24 hours by 5%, 10%, and 15%, respectively. In addition, the half-maximal voltage required for IK activation was shifted from +34 mV in the nonstretched cells to -5 mV in the stretched cells. Although IK in both groups of CMECs was blocked to a similar extent by tetraethylammonium, currents in the stretched endothelial cells displayed an enhanced sensitivity to inhibition by charybdotoxin. Preincubation of the CMECs with either pertussis toxin or phorbol 12-myristate 13-acetate during the 24 hours of cell stretch did not prevent the increase in IK. The application of phorbol 12-myristate 13-acetate and static stretch stimulated the proliferation of CMECs. Stretch-induced regulation of K+ channels may be important to control the resting potential of the endothelium and may contribute to capillary growth during periods of mechanical perturbation.  (+info)

Charybdotoxin and apamin block EDHF in rat mesenteric artery if selectively applied to the endothelium. (7/460)

In rat mesenteric artery, endothelium-derived hyperpolarizing factor (EDHF) is blocked by a combination of apamin and charybdotoxin (ChTX). The site of action of these toxins has not been established. We compared the effects of ChTX and apamin applied selectively to the endothelium and to the smooth muscle. In isometrically mounted arteries, ACh (0.01-10 micrometers), in the presence of indomethacin (2.8 microM) and Nomega-nitro-L-arginine methyl ester (L-NAME) (100 microM), concentration dependently relaxed phenylephrine (PE)-stimulated tone (EC50 50 nM; n = 10). Apamin (50 nM) and ChTX (50 nM) abolished this relaxation (n = 5). In pressurized arteries, ACh (10 microM), applied intraluminally in the presence of indomethacin (2.8 microM) and L-NAME (100 microM), dilated both PE-stimulated (0.3-0.5 microM; n = 5) and myogenic tone (n = 3). Apamin (50 nM ) and ChTX (50 nM) applied intraluminally abolished ACh-induced dilatations. Bath superperfusion of apamin and ChTX did not affect ACh-induced dilatations of either PE-stimulated (n = 5) or myogenic tone (n = 3). This is the first demonstration that ChTX and apamin act selectively on the endothelium to block EDHF-mediated relaxation.  (+info)

Differential effects of pinacidil, cromakalim, and NS 1619 on electrically evoked contractions in rat vas deferens. (8/460)

AIM: To compare the inhibitory action of electrically evoked contractions of rat epididymal vas deferens by pinacidil (Pin), cromakalim (Cro), and NS 1619. METHODS: Monophasic contractions were evoked by electric field stimulation in rat isolated epididymal half of vas deferens. RESULTS: Newly developed ATP-sensitive K+ channel openers, Pin and Cro, concentration-dependently reduced the electrically evoked (0.3 Hz, 1 ms pulse duration, 60 V) contractions and glibenclamide but not charybdotoxin antagonized the inhibitory effects of both agents. Pin shifted the concentration-response curve for norepinephrine to the right with reducing the magnitude of the maximum contraction in a glibenclamide-sensitive fashion. The large-conductance Ca(2+)-activated K+ channel opener, NS 1619, inhibited the electrically evoked contractions in a concentration-dependent manner. Charybdotoxin (100 nmol.L-1) partially reduced the effect of NS 1619 but glibenclamide (10 mumol.L-1) showed no effect. None of these 3 agents affected the basal tension. CONCLUSION: Both ATP-sensitive and Ca(2+)-activated K+ channels presented in vas deferens smooth muscles involved in regulation of muscle contractility.  (+info)

Charybdotoxin is a neurotoxin that is derived from the venom of the death stalker scorpion (Leiurus quinquestriatus). It specifically binds to and blocks certain types of ion channels called "big potassium" or "BK" channels, which are found in various tissues including smooth muscle, nerve, and endocrine cells. By blocking these channels, charybdotoxin can alter the electrical activity of cells and potentially affect a variety of physiological processes. It is an important tool in basic research for studying the structure and function of BK channels and their role in various diseases.

Scorpion venoms are complex mixtures of neurotoxins, enzymes, and other bioactive molecules that are produced by the venom glands of scorpions. These venoms are primarily used for prey immobilization and defense. The neurotoxins found in scorpion venoms can cause a variety of symptoms in humans, including pain, swelling, numbness, and in severe cases, respiratory failure and death.

Scorpion venoms are being studied for their potential medical applications, such as in the development of new pain medications and insecticides. Additionally, some components of scorpion venom have been found to have antimicrobial properties and may be useful in the development of new antibiotics.

Apamin is a neurotoxin found in the venom of the honeybee (Apis mellifera). It is a small peptide consisting of 18 amino acids and has a molecular weight of approximately 2000 daltons. Apamin is known to selectively block certain types of calcium-activated potassium channels, which are involved in the regulation of neuronal excitability. It has been used in scientific research to study the role of these ion channels in various physiological processes.

Clinically, apamin has been investigated for its potential therapeutic effects in a variety of neurological disorders, such as epilepsy and Parkinson's disease. However, its use as a therapeutic agent is not yet approved by regulatory agencies due to the lack of sufficient clinical evidence and concerns about its potential toxicity.

Potassium channels are membrane proteins that play a crucial role in regulating the electrical excitability of cells, including cardiac, neuronal, and muscle cells. These channels facilitate the selective passage of potassium ions (K+) across the cell membrane, maintaining the resting membrane potential and shaping action potentials. They are composed of four or six subunits that assemble to form a central pore through which potassium ions move down their electrochemical gradient. Potassium channels can be modulated by various factors such as voltage, ligands, mechanical stimuli, or temperature, allowing cells to fine-tune their electrical properties and respond to different physiological demands. Dysfunction of potassium channels has been implicated in several diseases, including cardiac arrhythmias, epilepsy, and neurodegenerative disorders.

Potassium channel blockers are a class of medications that work by blocking potassium channels, which are proteins in the cell membrane that control the movement of potassium ions into and out of cells. By blocking these channels, potassium channel blockers can help to regulate electrical activity in the heart, making them useful for treating certain types of cardiac arrhythmias (irregular heart rhythms).

There are several different types of potassium channel blockers, including:

1. Class III antiarrhythmic drugs: These medications, such as amiodarone and sotalol, are used to treat and prevent serious ventricular arrhythmias (irregular heart rhythms that originate in the lower chambers of the heart).
2. Calcium channel blockers: While not strictly potassium channel blockers, some calcium channel blockers also have effects on potassium channels. These medications, such as diltiazem and verapamil, are used to treat hypertension (high blood pressure), angina (chest pain), and certain types of arrhythmias.
3. Non-selective potassium channel blockers: These medications, such as 4-aminopyridine and tetraethylammonium, have a broader effect on potassium channels and are used primarily in research settings to study the electrical properties of cells.

It's important to note that potassium channel blockers can have serious side effects, particularly when used in high doses or in combination with other medications that affect heart rhythms. They should only be prescribed by a healthcare provider who is familiar with their use and potential risks.

Biological factors are the aspects related to living organisms, including their genes, evolution, physiology, and anatomy. These factors can influence an individual's health status, susceptibility to diseases, and response to treatments. Biological factors can be inherited or acquired during one's lifetime and can interact with environmental factors to shape a person's overall health. Examples of biological factors include genetic predisposition, hormonal imbalances, infections, and chronic medical conditions.

Calcium-activated potassium channels are a type of ion channel found in the membranes of cells. These channels are activated by an increase in intracellular calcium levels and play a crucial role in regulating various cellular processes, including electrical excitability, neurotransmitter release, hormone secretion, and vascular tone.

Once activated, calcium-activated potassium channels allow potassium ions (K+) to flow out of the cell, which can lead to membrane hyperpolarization or stabilization of the resting membrane potential. This process helps control the frequency and duration of action potentials in excitable cells such as neurons and muscle fibers.

There are several subtypes of calcium-activated potassium channels, including:

1. Large conductance calcium-activated potassium (BK) channels: These channels have a large single-channel conductance and are activated by both voltage and intracellular calcium. They play essential roles in regulating vascular tone, neurotransmitter release, and neuronal excitability.
2. Small conductance calcium-activated potassium (SK) channels: These channels have a smaller single-channel conductance and are primarily activated by intracellular calcium. They contribute to the regulation of neuronal excitability and neurotransmitter release.
3. Intermediate conductance calcium-activated potassium (IK) channels: These channels have an intermediate single-channel conductance and are activated by both voltage and intracellular calcium. They play a role in regulating epithelial ion transport, smooth muscle cell excitability, and neurotransmitter release.

Dysfunction of calcium-activated potassium channels has been implicated in various pathological conditions, such as hypertension, epilepsy, chronic pain, and neurological disorders.

Tetraethylammonium (TEA) is not typically defined in the context of medical terminology, but rather it is a chemical compound with the formula (C2H5)4N+. It is used in research and development, particularly in the field of electrophysiology where it is used as a blocking agent for certain types of ion channels.

Medically, TEA may be mentioned in the context of its potential toxicity or adverse effects on the human body. Exposure to TEA can cause symptoms such as nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, and confusion. Severe exposure can lead to more serious complications, including seizures, respiratory failure, and cardiac arrest.

Therefore, while Tetraethylammonium is not a medical term per se, it is important for healthcare professionals to be aware of its potential health hazards and take appropriate precautions when handling or working with this compound.

4-Aminopyridine is a type of medication that is used to treat symptoms of certain neurological disorders, such as multiple sclerosis or spinal cord injuries. It works by blocking the action of potassium channels in nerve cells, which helps to improve the transmission of nerve impulses and enhance muscle function.

The chemical name for 4-Aminopyridine is 4-AP or fampridine. It is available as a prescription medication in some countries and can be taken orally in the form of tablets or capsules. Common side effects of 4-Aminopyridine include dizziness, lightheadedness, and numbness or tingling sensations in the hands or feet.

It is important to note that 4-Aminopyridine should only be used under the supervision of a healthcare professional, as it can have serious side effects if not used properly.

Intermediate-conductance calcium-activated potassium channels (IKCa) are a type of ion channel found in various cell types, including immune cells, endothelial cells, and neurons. These channels are activated by an increase in intracellular calcium ions (Ca2+) and allow the flow of potassium ions (K+) out of the cell.

IKCa channels have a single-channel conductance that is intermediate between small-conductance (SKCa) and large-conductance (BKCa) calcium-activated potassium channels, typically ranging from 20 to 100 picosiemens (pS). They are encoded by the KCNN4 gene in humans.

The activation of IKCa channels plays a crucial role in regulating various cellular processes, such as membrane potential, calcium signaling, and immune response. For example, in activated immune cells, the opening of IKCa channels helps to repolarize the membrane potential and limit further Ca2+ entry into the cell, thereby modulating cytokine production and inflammatory responses. In endothelial cells, IKCa channel activation can regulate vascular tone and blood flow by controlling the diameter of blood vessels.

Glyburide is a medication that falls under the class of drugs known as sulfonylureas. It is primarily used to manage type 2 diabetes by lowering blood sugar levels. Glyburide works by stimulating the release of insulin from the pancreas, thereby increasing the amount of insulin available in the body to help glucose enter cells and decrease the level of glucose in the bloodstream.

The medical definition of Glyburide is:
A second-generation sulfonylurea antidiabetic drug (oral hypoglycemic) used in the management of type 2 diabetes mellitus. It acts by stimulating pancreatic beta cells to release insulin and increases peripheral glucose uptake and utilization, thereby reducing blood glucose levels. Glyburide may also decrease glucose production in the liver.

It is important to note that Glyburide should be used as part of a comprehensive diabetes management plan that includes proper diet, exercise, regular monitoring of blood sugar levels, and other necessary lifestyle modifications. As with any medication, it can have side effects and potential interactions with other drugs, so it should only be taken under the supervision of a healthcare provider.

Vasodilation is the widening or increase in diameter of blood vessels, particularly the involuntary relaxation of the smooth muscle in the tunica media (middle layer) of the arteriole walls. This results in an increase in blood flow and a decrease in vascular resistance. Vasodilation can occur due to various physiological and pathophysiological stimuli, such as local metabolic demands, neural signals, or pharmacological agents. It plays a crucial role in regulating blood pressure, tissue perfusion, and thermoregulation.

Membrane potential is the electrical potential difference across a cell membrane, typically for excitable cells such as nerve and muscle cells. It is the difference in electric charge between the inside and outside of a cell, created by the selective permeability of the cell membrane to different ions. The resting membrane potential of a typical animal cell is around -70 mV, with the interior being negative relative to the exterior. This potential is generated and maintained by the active transport of ions across the membrane, primarily through the action of the sodium-potassium pump. Membrane potentials play a crucial role in many physiological processes, including the transmission of nerve impulses and the contraction of muscle cells.

Large-conductance calcium-activated potassium channels (BK channels) are a type of ion channel found in the membranes of many types of cells, including excitable cells such as neurons and muscle cells. These channels are characterized by their large conductance to potassium ions (K+), which allows them to significantly impact the electrical excitability of cells.

BK channels are activated by both voltage and intracellular calcium ions (Ca2+). They are therefore also known as Ca2+-activated K+ (KCa) channels. When the membrane potential becomes more positive (depolarized), and/or when intracellular Ca2+ levels rise, BK channels open, allowing K+ to flow out of the cell. This efflux of K+ tends to hyperpolarize the membrane potential, making it more difficult for the cell to generate further action potentials or contractile responses.

BK channels play important roles in regulating a variety of physiological processes, including neuronal excitability, neurotransmitter release, vascular tone, and cardiac electrical activity. Dysfunction of BK channels has been implicated in several diseases, such as hypertension, epilepsy, and chronic pain.

Muscle relaxation, in a medical context, refers to the process of reducing tension and promoting relaxation in the skeletal muscles. This can be achieved through various techniques, including progressive muscle relaxation (PMR), where individuals consciously tense and then release specific muscle groups in a systematic manner.

PMR has been shown to help reduce anxiety, stress, and muscle tightness, and improve overall well-being. It is often used as a complementary therapy in conjunction with other treatments for conditions such as chronic pain, headaches, and insomnia.

Additionally, muscle relaxation can also be facilitated through pharmacological interventions, such as the use of muscle relaxant medications. These drugs work by inhibiting the transmission of signals between nerves and muscles, leading to a reduction in muscle tone and spasticity. They are commonly used to treat conditions such as multiple sclerosis, cerebral palsy, and spinal cord injuries.

The mesenteric arteries are the arteries that supply oxygenated blood to the intestines. There are three main mesenteric arteries: the superior mesenteric artery, which supplies blood to the small intestine (duodenum to two-thirds of the transverse colon) and large intestine (cecum, ascending colon, and the first part of the transverse colon); the inferior mesenteric artery, which supplies blood to the distal third of the transverse colon, descending colon, sigmoid colon, and rectum; and the middle colic artery, which is a branch of the superior mesenteric artery that supplies blood to the transverse colon. These arteries are important in maintaining adequate blood flow to the intestines to support digestion and absorption of nutrients.

Clotrimazole is an antifungal medication used to treat various fungal infections such as athlete's foot, jock itch, ringworm, candidiasis (yeast infection), and oral thrush. It works by inhibiting the growth of fungi that cause these infections. Clotrimazole is available in several forms, including creams, lotions, powders, tablets, and lozenges.

The medical definition of Clotrimazole is:

A synthetic antifungal agent belonging to the imidazole class, used topically to treat various fungal infections such as candidiasis, tinea pedis, tinea cruris, and tinea versicolor. It works by inhibiting the biosynthesis of ergosterol, a key component of fungal cell membranes, leading to increased permeability and death of fungal cells.

Calcium is an essential mineral that is vital for various physiological processes in the human body. The medical definition of calcium is as follows:

Calcium (Ca2+) is a crucial cation and the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It plays a vital role in maintaining structural integrity, nerve impulse transmission, muscle contraction, hormonal secretion, blood coagulation, and enzyme activation.

Calcium homeostasis is tightly regulated through the interplay of several hormones, including parathyroid hormone (PTH), calcitonin, and vitamin D. Dietary calcium intake, absorption, and excretion are also critical factors in maintaining optimal calcium levels in the body.

Hypocalcemia refers to low serum calcium levels, while hypercalcemia indicates high serum calcium levels. Both conditions can have detrimental effects on various organ systems and require medical intervention to correct.

Acetylcholine is a neurotransmitter, a type of chemical messenger that transmits signals across a chemical synapse from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell. It is involved in both peripheral and central nervous system functions.

In the peripheral nervous system, acetylcholine acts as a neurotransmitter at the neuromuscular junction, where it transmits signals from motor neurons to activate muscles. Acetylcholine also acts as a neurotransmitter in the autonomic nervous system, where it is involved in both the sympathetic and parasympathetic systems.

In the central nervous system, acetylcholine plays a role in learning, memory, attention, and arousal. Disruptions in cholinergic neurotransmission have been implicated in several neurological disorders, including Alzheimer's disease, Parkinson's disease, and myasthenia gravis.

Acetylcholine is synthesized from choline and acetyl-CoA by the enzyme choline acetyltransferase and is stored in vesicles at the presynaptic terminal of the neuron. When a nerve impulse arrives, the vesicles fuse with the presynaptic membrane, releasing acetylcholine into the synapse. The acetylcholine then binds to receptors on the postsynaptic membrane, triggering a response in the target cell. Acetylcholine is subsequently degraded by the enzyme acetylcholinesterase, which terminates its action and allows for signal transduction to be repeated.

Vasodilator agents are pharmacological substances that cause the relaxation or widening of blood vessels by relaxing the smooth muscle in the vessel walls. This results in an increase in the diameter of the blood vessels, which decreases vascular resistance and ultimately reduces blood pressure. Vasodilators can be further classified based on their site of action:

1. Systemic vasodilators: These agents cause a generalized relaxation of the smooth muscle in the walls of both arteries and veins, resulting in a decrease in peripheral vascular resistance and preload (the volume of blood returning to the heart). Examples include nitroglycerin, hydralazine, and calcium channel blockers.
2. Arterial vasodilators: These agents primarily affect the smooth muscle in arterial vessel walls, leading to a reduction in afterload (the pressure against which the heart pumps blood). Examples include angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and direct vasodilators like sodium nitroprusside.
3. Venous vasodilators: These agents primarily affect the smooth muscle in venous vessel walls, increasing venous capacitance and reducing preload. Examples include nitroglycerin and other organic nitrates.

Vasodilator agents are used to treat various cardiovascular conditions such as hypertension, heart failure, angina, and pulmonary arterial hypertension. It is essential to monitor their use carefully, as excessive vasodilation can lead to orthostatic hypotension, reflex tachycardia, or fluid retention.

Potassium is a essential mineral and an important electrolyte that is widely distributed in the human body. The majority of potassium in the body (approximately 98%) is found within cells, with the remaining 2% present in blood serum and other bodily fluids. Potassium plays a crucial role in various physiological processes, including:

1. Regulation of fluid balance and maintenance of normal blood pressure through its effects on vascular tone and sodium excretion.
2. Facilitation of nerve impulse transmission and muscle contraction by participating in the generation and propagation of action potentials.
3. Protein synthesis, enzyme activation, and glycogen metabolism.
4. Regulation of acid-base balance through its role in buffering systems.

The normal serum potassium concentration ranges from 3.5 to 5.0 mEq/L (milliequivalents per liter) or mmol/L (millimoles per liter). Potassium levels outside this range can have significant clinical consequences, with both hypokalemia (low potassium levels) and hyperkalemia (high potassium levels) potentially leading to serious complications such as cardiac arrhythmias, muscle weakness, and respiratory failure.

Potassium is primarily obtained through the diet, with rich sources including fruits (e.g., bananas, oranges, and apricots), vegetables (e.g., leafy greens, potatoes, and tomatoes), legumes, nuts, dairy products, and meat. In cases of deficiency or increased needs, potassium supplements may be recommended under the guidance of a healthcare professional.

Barium compounds are inorganic substances that contain the metallic element barium (Ba) combined with one or more other elements. Barium is an alkaline earth metal that is highly reactive and toxic in its pure form. However, when bound with other elements to form barium compounds, it can be used safely for various medical and industrial purposes.

In medicine, barium compounds are commonly used as a contrast material for X-ray examinations of the digestive system. When a patient swallows a preparation containing barium sulfate, the dense compound coats the lining of the esophagus, stomach, and intestines, making them visible on an X-ray image. This allows doctors to diagnose conditions such as ulcers, tumors, or blockages in the digestive tract.

Other barium compounds include barium carbonate, barium chloride, and barium hydroxide, which are used in various industrial applications such as drilling muds, flame retardants, and pigments for paints and plastics. However, these compounds can be toxic if ingested or inhaled, so they must be handled with care.

I believe there may be some confusion in your question as "scorpions" are not a medical term, but instead refer to a type of arachnid. If you're asking about a medical condition that might involve scorpions, then perhaps you're referring to "scorpion stings."

Scorpion stings occur when a scorpion uses its venomous stinger to inject venom into another animal or human. The effects of a scorpion sting can vary greatly depending on the species of scorpion and the amount of venom injected, but generally, they can cause localized pain, swelling, and redness at the site of the sting. In more severe cases, symptoms such as numbness, difficulty breathing, muscle twitching, or convulsions may occur. Some species of scorpions have venom that can be life-threatening to humans, especially in children, the elderly, and those with compromised immune systems.

If you are looking for information on a specific medical condition or term, please provide more details so I can give you a more accurate answer.

Nitro-L-arginine or Nitroarginine is not a medical term per se, but it is a chemical compound that is sometimes used in medical research and experiments. It is a salt of nitric acid and L-arginine, an amino acid that is important for the functioning of the body.

Nitroarginine is known to inhibit the production of nitric oxide, a molecule that plays a role in various physiological processes such as blood flow regulation, immune response, and neurotransmission. As a result, nitroarginine has been used in research to study the effects of reduced nitric oxide levels on different systems in the body.

It's worth noting that nitroarginine is not approved for use as a medication in humans, and its use is generally limited to laboratory settings.

Tetraethylammonium compounds refer to chemical substances that contain the tetraethylammonium cation (N(C2H5)4+). This organic cation is derived from tetraethylammonium hydroxide, which in turn is produced by the reaction of ethyl alcohol with ammonia and then treated with a strong acid.

Tetraethylammonium compounds are used in various biomedical research applications as they can block certain types of ion channels, making them useful for studying neuronal excitability and neurotransmission. However, these compounds have also been associated with toxic effects on the nervous system and other organs, and their use is therefore subject to strict safety regulations.

The Kv1.3 potassium channel is a type of voltage-gated potassium channel that is widely expressed in various tissues, including immune cells such as T lymphocytes. It plays a crucial role in regulating the electrical activity of cells and controlling the flow of potassium ions across the cell membrane.

Kv1.3 channels are composed of four pore-forming alpha subunits, each containing six transmembrane domains. These channels open and close in response to changes in the membrane potential, allowing potassium ions to flow out of the cell when the channel is open. This movement of ions helps to restore the resting membrane potential and regulate the excitability of the cell.

In T lymphocytes, Kv1.3 channels are involved in the regulation of calcium signaling and activation of immune responses. They play a critical role in maintaining the membrane potential and controlling the release of calcium from intracellular stores, which is necessary for T-cell activation and proliferation. Inhibition or blockade of Kv1.3 channels has been shown to suppress T-cell activation and could have potential therapeutic implications in the treatment of autoimmune diseases and transplant rejection.

Endothelium-dependent relaxing factors (EDRFs) are substances that are released by the endothelial cells, which line the interior surface of blood vessels. These factors cause relaxation of the smooth muscle in the vessel wall, leading to vasodilation and an increase in blood flow. One of the most well-known EDRFs is nitric oxide (NO), which is produced from the amino acid L-arginine by the enzyme nitric oxide synthase. Other substances that have been identified as EDRFs include prostacyclin and endothelium-derived hyperpolarizing factor (EDHF). These factors play important roles in the regulation of vascular tone, blood pressure, and inflammation.

Cromakalim is a pharmacological agent, specifically a potassium channel opener, that was investigated for its potential therapeutic effects in the treatment of cardiovascular diseases such as hypertension and angina. Potassium channel openers work by relaxing smooth muscle cells in blood vessels, which leads to vasodilation and decreased blood pressure. However, cromakalim was never approved for clinical use due to its associated side effects, including negative inotropic effects on the heart and potential proarrhythmic properties.

Elapid venoms are the toxic secretions produced by elapid snakes, a family of venomous snakes that includes cobras, mambas, kraits, and coral snakes. These venoms are primarily composed of neurotoxins, which can cause paralysis and respiratory failure in prey or predators.

Elapid venoms work by targeting the nervous system, disrupting communication between the brain and muscles. This results in muscle weakness, paralysis, and eventually respiratory failure if left untreated. Some elapid venoms also contain hemotoxins, which can cause tissue damage, bleeding, and other systemic effects.

The severity of envenomation by an elapid snake depends on several factors, including the species of snake, the amount of venom injected, the location of the bite, and the size and health of the victim. Prompt medical treatment is essential in cases of elapid envenomation, as the effects of the venom can progress rapidly and lead to serious complications or death if left untreated.

Neurotoxins are substances that are poisonous or destructive to nerve cells (neurons) and the nervous system. They can cause damage by destroying neurons, disrupting communication between neurons, or interfering with the normal functioning of the nervous system. Neurotoxins can be produced naturally by certain organisms, such as bacteria, plants, and animals, or they can be synthetic compounds created in a laboratory. Examples of neurotoxins include botulinum toxin (found in botulism), tetrodotoxin (found in pufferfish), and heavy metals like lead and mercury. Neurotoxic effects can range from mild symptoms such as headaches, muscle weakness, and tremors, to more severe symptoms such as paralysis, seizures, and cognitive impairment. Long-term exposure to neurotoxins can lead to chronic neurological conditions and other health problems.

The endothelium is a thin layer of simple squamous epithelial cells that lines the interior surface of blood vessels, lymphatic vessels, and heart chambers. The vascular endothelium, specifically, refers to the endothelial cells that line the blood vessels. These cells play a crucial role in maintaining vascular homeostasis by regulating vasomotor tone, coagulation, platelet activation, inflammation, and permeability of the vessel wall. They also contribute to the growth and repair of the vascular system and are involved in various pathological processes such as atherosclerosis, hypertension, and diabetes.

Nitric oxide (NO) is a molecule made up of one nitrogen atom and one oxygen atom. In the body, it is a crucial signaling molecule involved in various physiological processes such as vasodilation, immune response, neurotransmission, and inhibition of platelet aggregation. It is produced naturally by the enzyme nitric oxide synthase (NOS) from the amino acid L-arginine. Inhaled nitric oxide is used medically to treat pulmonary hypertension in newborns and adults, as it helps to relax and widen blood vessels, improving oxygenation and blood flow.

I'm sorry for any confusion, but "picolines" is not a term commonly used in medical definitions. It is a term that refers to a group of chemical compounds known as methylated benzenes or xylenols. They have some industrial uses, but they are not typically relevant in the context of medical definitions or healthcare. If you have any questions related to medical terminology or health concerns, I'd be happy to try and help with those instead!

Patch-clamp techniques are a group of electrophysiological methods used to study ion channels and other electrical properties of cells. These techniques were developed by Erwin Neher and Bert Sakmann, who were awarded the Nobel Prize in Physiology or Medicine in 1991 for their work. The basic principle of patch-clamp techniques involves creating a high resistance seal between a glass micropipette and the cell membrane, allowing for the measurement of current flowing through individual ion channels or groups of channels.

There are several different configurations of patch-clamp techniques, including:

1. Cell-attached configuration: In this configuration, the micropipette is attached to the outer surface of the cell membrane, and the current flowing across a single ion channel can be measured. This configuration allows for the study of the properties of individual channels in their native environment.
2. Whole-cell configuration: Here, the micropipette breaks through the cell membrane, creating a low resistance electrical connection between the pipette and the inside of the cell. This configuration allows for the measurement of the total current flowing across all ion channels in the cell membrane.
3. Inside-out configuration: In this configuration, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the inner surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in isolation from other cellular components.
4. Outside-out configuration: Here, the micropipette is pulled away from the cell after establishing a seal, resulting in the exposure of the outer surface of the cell membrane to the solution in the pipette. This configuration allows for the study of the properties of ion channels in their native environment, but with the ability to control the composition of the extracellular solution.

Patch-clamp techniques have been instrumental in advancing our understanding of ion channel function and have contributed to numerous breakthroughs in neuroscience, pharmacology, and physiology.

A smooth muscle within the vascular system refers to the involuntary, innervated muscle that is found in the walls of blood vessels. These muscles are responsible for controlling the diameter of the blood vessels, which in turn regulates blood flow and blood pressure. They are called "smooth" muscles because their individual muscle cells do not have the striations, or cross-striped patterns, that are observed in skeletal and cardiac muscle cells. Smooth muscle in the vascular system is controlled by the autonomic nervous system and by hormones, and can contract or relax slowly over a period of time.

Large-conductance calcium-activated potassium channels, also known as BK channels, are a type of ion channel that are activated by both voltage and the presence of intracellular calcium ions. The alpha subunit is one of the four subunits that make up the functional channel. The alpha subunit contains the central pore of the channel through which potassium ions flow, as well as the binding sites for calcium ions that allow the channel to be activated. These channels play a crucial role in regulating vascular tone, neurotransmitter release and excitability of many types of cells. Mutations in the gene encoding the alpha subunit can lead to various human diseases, such as hypertension, epilepsy, and autism.

Small-conductance calcium-activated potassium channels (SK channels) are a type of ion channel found in the membranes of excitable cells, such as neurons and muscle cells. They are called "calcium-activated" because their opening is triggered by an increase in intracellular calcium ions (Ca2+), and "potassium channels" because they are selectively permeable to potassium ions (K+).

SK channels have a small conductance, meaning that they allow only a relatively small number of ions to pass through them at any given time. This makes them less influential in shaping the electrical properties of cells compared to other types of potassium channels with larger conductances.

SK channels play important roles in regulating neuronal excitability and neurotransmitter release, as well as controlling the contraction and relaxation of smooth muscle cells. They are activated by calcium ions that enter the cell through voltage-gated calcium channels or other types of Ca2+ channels, and their opening leads to an efflux of K+ ions from the cell. This efflux of positive charges tends to hyperpolarize the membrane potential, making it more difficult for the cell to generate action potentials and release neurotransmitters.

There are three subtypes of SK channels, designated as SK1, SK2, and SK3, which differ in their biophysical properties and sensitivity to pharmacological agents. These channels have been implicated in a variety of physiological processes, including learning and memory, pain perception, blood pressure regulation, and the pathogenesis of certain neurological disorders.

Indomethacin is a non-steroidal anti-inflammatory drug (NSAID) that is commonly used to reduce pain, inflammation, and fever. It works by inhibiting the activity of certain enzymes in the body, including cyclooxygenase (COX), which plays a role in producing prostaglandins, chemicals involved in the inflammatory response.

Indomethacin is available in various forms, such as capsules, suppositories, and injectable solutions, and is used to treat a wide range of conditions, including rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, gout, and bursitis. It may also be used to relieve pain and reduce fever in other conditions, such as dental procedures or after surgery.

Like all NSAIDs, indomethacin can have side effects, including stomach ulcers, bleeding, and kidney damage, especially when taken at high doses or for long periods of time. It may also increase the risk of heart attack and stroke. Therefore, it is important to use indomethacin only as directed by a healthcare provider and to report any unusual symptoms or side effects promptly.

NG-Nitroarginine Methyl Ester (L-NAME) is not a medication, but rather a research chemical used in scientific studies. It is an inhibitor of nitric oxide synthase, an enzyme that synthesizes nitric oxide, a molecule involved in the relaxation of blood vessels.

Therefore, L-NAME is often used in experiments to investigate the role of nitric oxide in various physiological and pathophysiological processes. It is important to note that the use of L-NAME in humans is not approved for therapeutic purposes due to its potential side effects, which can include hypertension, decreased renal function, and decreased cerebral blood flow.

Molsidomine is a medication that belongs to a class of drugs called vasodilators. It works by relaxing and widening blood vessels, which helps to improve blood flow and reduce the workload on the heart. Molsidomine is used to treat chronic stable angina (chest pain caused by reduced blood flow to the heart) and has been found to be effective in reducing the frequency and severity of anginal attacks.

When molsidomine is absorbed into the body, it is converted into its active metabolite, SIN-1, which is responsible for its vasodilatory effects. SIN-1 causes smooth muscle relaxation by increasing the levels of nitric oxide in the blood vessels, leading to their dilation and improved blood flow.

Molsidomine is available in tablet form and is typically taken two to three times a day, with or without food. Common side effects of molsidomine include headache, dizziness, flushing, and palpitations. It should be used with caution in patients with low blood pressure, heart failure, or impaired kidney function.

Voltage-gated potassium channels are a type of ion channel found in the membrane of excitable cells such as nerve and muscle cells. They are called "voltage-gated" because their opening and closing is regulated by the voltage, or electrical potential, across the cell membrane. Specifically, these channels are activated when the membrane potential becomes more positive, a condition that occurs during the action potential of a neuron or muscle fiber.

When voltage-gated potassium channels open, they allow potassium ions (K+) to flow out of the cell down their electrochemical gradient. This outward flow of K+ ions helps to repolarize the membrane, bringing it back to its resting potential after an action potential has occurred. The precise timing and duration of the opening and closing of voltage-gated potassium channels is critical for the normal functioning of excitable cells, and abnormalities in these channels have been linked to a variety of diseases, including cardiac arrhythmias, epilepsy, and neurological disorders.

Oxadiazoles are heterocyclic compounds containing a five-membered ring consisting of two carbon atoms, one nitrogen atom, and two oxygen atoms in an alternating sequence. There are three possible isomers of oxadiazole, depending on the position of the nitrogen atom: 1,2,3-oxadiazole, 1,2,4-oxadiazole, and 1,3,4-oxadiazole. These compounds have significant interest in medicinal chemistry due to their diverse biological activities, including anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer properties. Some oxadiazoles also exhibit potential as contrast agents for medical imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT).

Enzyme inhibitors are substances that bind to an enzyme and decrease its activity, preventing it from catalyzing a chemical reaction in the body. They can work by several mechanisms, including blocking the active site where the substrate binds, or binding to another site on the enzyme to change its shape and prevent substrate binding. Enzyme inhibitors are often used as drugs to treat various medical conditions, such as high blood pressure, abnormal heart rhythms, and bacterial infections. They can also be found naturally in some foods and plants, and can be used in research to understand enzyme function and regulation.

Electrophysiology is a branch of medicine that deals with the electrical activities of the body, particularly the heart. In a medical context, electrophysiology studies (EPS) are performed to assess abnormal heart rhythms (arrhythmias) and to evaluate the effectiveness of certain treatments, such as medication or pacemakers.

During an EPS, electrode catheters are inserted into the heart through blood vessels in the groin or neck. These catheters can record the electrical activity of the heart and stimulate it to help identify the source of the arrhythmia. The information gathered during the study can help doctors determine the best course of treatment for each patient.

In addition to cardiac electrophysiology, there are also other subspecialties within electrophysiology, such as neuromuscular electrophysiology, which deals with the electrical activity of the nervous system and muscles.

Large-conductance calcium-activated potassium channels, also known as BK channels, are a type of ion channel that are activated by both voltage and increases in intracellular calcium concentrations. The pore-forming α subunit of the BK channel can be modulated by accessory β subunits, which are referred to as "large-conductance calcium-activated potassium channel beta subunits."

These β subunits are a family of proteins that consist of four members (β1-β4) and play a critical role in regulating the function of BK channels. They can modulate the activation kinetics, voltage dependence, and calcium sensitivity of the BK channel by binding to the α subunit.

The β subunits have distinct expression patterns and functions. For example, the β1 subunit is widely expressed in various tissues, including neurons, smooth muscle cells, and secretory cells, and it can slow down the activation kinetics of BK channels. The β2 subunit is predominantly expressed in neurons and can shift the voltage dependence of BK channel activation to more negative potentials. The β3 subunit is also primarily expressed in neurons and can reduce the calcium sensitivity of BK channels. Finally, the β4 subunit is mainly found in the brain and can inhibit BK channel activity.

Overall, large-conductance calcium-activated potassium channel beta subunits play a crucial role in regulating the function of BK channels, which are involved in various physiological processes, including neuronal excitability, muscle contraction, and hormone secretion.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

"Wistar rats" are a strain of albino rats that are widely used in laboratory research. They were developed at the Wistar Institute in Philadelphia, USA, and were first introduced in 1906. Wistar rats are outbred, which means that they are genetically diverse and do not have a fixed set of genetic characteristics like inbred strains.

Wistar rats are commonly used as animal models in biomedical research because of their size, ease of handling, and relatively low cost. They are used in a wide range of research areas, including toxicology, pharmacology, nutrition, cancer, cardiovascular disease, and behavioral studies. Wistar rats are also used in safety testing of drugs, medical devices, and other products.

Wistar rats are typically larger than many other rat strains, with males weighing between 500-700 grams and females weighing between 250-350 grams. They have a lifespan of approximately 2-3 years. Wistar rats are also known for their docile and friendly nature, making them easy to handle and work with in the laboratory setting.

The Shaker superfamily of potassium channels, also known as Kv channels (voltage-gated potassium channels), refers to a group of ion channels that are responsible for the selective transport of potassium ions across the cell membrane. These channels are crucial for regulating the electrical excitability of cells, particularly in neurons and muscle cells.

The Shaker superfamily is named after the Drosophila melanogaster (fruit fly) gene shaker, which was the first voltage-gated potassium channel to be identified and cloned. The channels in this family share a common structure, consisting of four subunits that each contain six transmembrane domains. The fourth domain contains the voltage sensor, which responds to changes in membrane potential and triggers the opening or closing of the channel pore.

The Shaker superfamily is further divided into several subfamilies based on their sequence similarity and functional properties. These include the Shaw, Shab, and Shal subfamilies, among others. Each subfamily has distinct biophysical and pharmacological properties that allow for selective activation or inhibition by various drugs and toxins.

Overall, the Shaker superfamily of potassium channels plays a critical role in maintaining the electrical excitability of cells and is involved in a wide range of physiological processes, including nerve impulse transmission, muscle contraction, and hormone secretion.

Electric conductivity, also known as electrical conductance, is a measure of a material's ability to allow the flow of electric current through it. It is usually measured in units of Siemens per meter (S/m) or ohm-meters (Ω-m).

In medical terms, electric conductivity can refer to the body's ability to conduct electrical signals, which is important for various physiological processes such as nerve impulse transmission and muscle contraction. Abnormalities in electrical conductivity can be associated with various medical conditions, including neurological disorders and heart diseases.

For example, in electrocardiography (ECG), the electric conductivity of the heart is measured to assess its electrical activity and identify any abnormalities that may indicate heart disease. Similarly, in electromyography (EMG), the electric conductivity of muscles is measured to diagnose neuromuscular disorders.

Smooth muscle, also known as involuntary muscle, is a type of muscle that is controlled by the autonomic nervous system and functions without conscious effort. These muscles are found in the walls of hollow organs such as the stomach, intestines, bladder, and blood vessels, as well as in the eyes, skin, and other areas of the body.

Smooth muscle fibers are shorter and narrower than skeletal muscle fibers and do not have striations or sarcomeres, which give skeletal muscle its striped appearance. Smooth muscle is controlled by the autonomic nervous system through the release of neurotransmitters such as acetylcholine and norepinephrine, which bind to receptors on the smooth muscle cells and cause them to contract or relax.

Smooth muscle plays an important role in many physiological processes, including digestion, circulation, respiration, and elimination. It can also contribute to various medical conditions, such as hypertension, gastrointestinal disorders, and genitourinary dysfunction, when it becomes overactive or underactive.

I must clarify that the term "Guinea Pigs" is not typically used in medical definitions. However, in colloquial or informal language, it may refer to people who are used as the first to try out a new medical treatment or drug. This is known as being a "test subject" or "in a clinical trial."

In the field of scientific research, particularly in studies involving animals, guinea pigs are small rodents that are often used as experimental subjects due to their size, cost-effectiveness, and ease of handling. They are not actually pigs from Guinea, despite their name's origins being unclear. However, they do not exactly fit the description of being used in human medical experiments.

Bradykinin is a naturally occurring peptide in the human body, consisting of nine amino acids. It is a potent vasodilator and increases the permeability of blood vessels, causing a local inflammatory response. Bradykinin is formed from the breakdown of certain proteins, such as kininogen, by enzymes called kininases or proteases, including kallikrein. It plays a role in several physiological processes, including pain transmission, blood pressure regulation, and the immune response. In some pathological conditions, such as hereditary angioedema, bradykinin levels can increase excessively, leading to symptoms like swelling, redness, and pain.

Barium is a naturally occurring, silvery-white metallic chemical element with the symbol Ba and atomic number 56. In medical terms, barium is commonly used as a contrast agent in radiology, particularly in X-ray examinations such as an upper GI series or barium enema. The barium sulfate powder is mixed with water to create a liquid or thick paste that is swallowed or inserted through the rectum. This provides a white coating on the inside lining of the digestive tract, allowing it to be seen more clearly on X-ray images and helping doctors diagnose various conditions such as ulcers, tumors, or inflammation.

It's important to note that barium is not absorbed by the body and does not cause any harm when used in medical imaging procedures. However, if it is accidentally inhaled or aspirated into the lungs during administration, it can cause chemical pneumonitis, a potentially serious condition. Therefore, it should only be administered under the supervision of trained medical professionals.

Peptides are short chains of amino acid residues linked by covalent bonds, known as peptide bonds. They are formed when two or more amino acids are joined together through a condensation reaction, which results in the elimination of a water molecule and the formation of an amide bond between the carboxyl group of one amino acid and the amino group of another.

Peptides can vary in length from two to about fifty amino acids, and they are often classified based on their size. For example, dipeptides contain two amino acids, tripeptides contain three, and so on. Oligopeptides typically contain up to ten amino acids, while polypeptides can contain dozens or even hundreds of amino acids.

Peptides play many important roles in the body, including serving as hormones, neurotransmitters, enzymes, and antibiotics. They are also used in medical research and therapeutic applications, such as drug delivery and tissue engineering.

Calcium channel blockers (CCBs) are a class of medications that work by inhibiting the influx of calcium ions into cardiac and smooth muscle cells. This action leads to relaxation of the muscles, particularly in the blood vessels, resulting in decreased peripheral resistance and reduced blood pressure. Calcium channel blockers also have anti-arrhythmic effects and are used in the management of various cardiovascular conditions such as hypertension, angina, and certain types of arrhythmias.

Calcium channel blockers can be further classified into two main categories based on their chemical structure: dihydropyridines (e.g., nifedipine, amlodipine) and non-dihydropyridines (e.g., verapamil, diltiazem). Dihydropyridines are more selective for vascular smooth muscle and have a greater effect on blood pressure than heart rate or conduction. Non-dihydropyridines have a more significant impact on cardiac conduction and contractility, in addition to their vasodilatory effects.

It is important to note that calcium channel blockers may interact with other medications and should be used under the guidance of a healthcare professional. Potential side effects include dizziness, headache, constipation, and peripheral edema.

Calcium channel agonists are substances that increase the activity or function of calcium channels. Calcium channels are specialized proteins in cell membranes that regulate the flow of calcium ions into and out of cells. They play a crucial role in various physiological processes, including muscle contraction, hormone secretion, and nerve impulse transmission.

Calcium channel agonists can enhance the opening of these channels, leading to an increased influx of calcium ions into the cells. This can result in various pharmacological effects, depending on the type of cell and tissue involved. For example, calcium channel agonists may be used to treat conditions such as hypotension (low blood pressure) or heart block by increasing cardiac contractility and heart rate. However, these agents should be used with caution due to their potential to cause adverse effects, including increased heart rate, hypertension, and arrhythmias.

Examples of calcium channel agonists include drugs such as Bay K 8644, FPL 64176, and A23187. It's important to note that some substances can act as both calcium channel agonists and antagonists, depending on the dose, concentration, or duration of exposure.

Nitric Oxide Synthase (NOS) is a group of enzymes that catalyze the production of nitric oxide (NO) from L-arginine. There are three distinct isoforms of NOS, each with different expression patterns and functions:

1. Neuronal Nitric Oxide Synthase (nNOS or NOS1): This isoform is primarily expressed in the nervous system and plays a role in neurotransmission, synaptic plasticity, and learning and memory processes.
2. Inducible Nitric Oxide Synthase (iNOS or NOS2): This isoform is induced by various stimuli such as cytokines, lipopolysaccharides, and hypoxia in a variety of cells including immune cells, endothelial cells, and smooth muscle cells. iNOS produces large amounts of NO, which functions as a potent effector molecule in the immune response, particularly in the defense against microbial pathogens.
3. Endothelial Nitric Oxide Synthase (eNOS or NOS3): This isoform is constitutively expressed in endothelial cells and produces low levels of NO that play a crucial role in maintaining vascular homeostasis by regulating vasodilation, inhibiting platelet aggregation, and preventing smooth muscle cell proliferation.

Overall, NOS plays an essential role in various physiological processes, including neurotransmission, immune response, cardiovascular function, and respiratory regulation. Dysregulation of NOS activity has been implicated in several pathological conditions such as hypertension, atherosclerosis, neurodegenerative diseases, and inflammatory disorders.

Benzopyrans are a class of chemical compounds that contain a benzene ring fused to a pyran ring. They are also known as chromenes. Benzopyrans can be found in various natural sources, including plants and fungi, and have been studied for their potential biological activities. Some benzopyrans have been found to have anti-inflammatory, antioxidant, and anticancer properties. However, some benzopyrans can also be toxic or have other adverse health effects, so it is important to study their properties and potential uses carefully.

nitroprusside (ni-troe-rus-ide)

A rapid-acting vasodilator used in the management of severe hypertension, acute heart failure, and to reduce afterload in patients undergoing cardiac surgery. It is a potent arterial and venous dilator that decreases preload and afterload, thereby reducing myocardial oxygen demand. Nitroprusside is metabolized to cyanide, which must be monitored closely during therapy to prevent toxicity.

Pharmacologic class: Peripheral vasodilators

Therapeutic class: Antihypertensives, Vasodilators

Medical Categories: Cardiovascular Drugs, Hypertension Agents

Quinoxalines are not a medical term, but rather an organic chemical compound. They are a class of heterocyclic aromatic compounds made up of a benzene ring fused to a pyrazine ring. Quinoxalines have no specific medical relevance, but some of their derivatives have been synthesized and used in medicinal chemistry as antibacterial, antifungal, and antiviral agents. They are also used in the production of dyes and pigments.

Arterioles are small branches of arteries that play a crucial role in regulating blood flow and blood pressure within the body's circulatory system. They are the smallest type of blood vessels that have muscular walls, which allow them to contract or dilate in response to various physiological signals.

Arterioles receive blood from upstream arteries and deliver it to downstream capillaries, where the exchange of oxygen, nutrients, and waste products occurs between the blood and surrounding tissues. The contraction of arteriolar muscles can reduce the diameter of these vessels, causing increased resistance to blood flow and leading to a rise in blood pressure upstream. Conversely, dilation of arterioles reduces resistance and allows for greater blood flow at a lower pressure.

The regulation of arteriolar tone is primarily controlled by the autonomic nervous system, local metabolic factors, and various hormones. This fine-tuning of arteriolar diameter enables the body to maintain adequate blood perfusion to vital organs while also controlling overall blood pressure and distribution.

Ion channel gating refers to the process by which ion channels in cell membranes open and close in response to various stimuli, allowing ions such as sodium, potassium, and calcium to flow into or out of the cell. This movement of ions is crucial for many physiological processes, including the generation and transmission of electrical signals in nerve cells, muscle contraction, and the regulation of hormone secretion.

Ion channel gating can be regulated by various factors, including voltage changes across the membrane (voltage-gated channels), ligand binding (ligand-gated channels), mechanical stress (mechanosensitive channels), or other intracellular signals (second messenger-gated channels). The opening and closing of ion channels are highly regulated and coordinated processes that play a critical role in maintaining the proper functioning of cells and organ systems.

Potassium chloride is an essential electrolyte that is often used in medical settings as a medication. It's a white, crystalline salt that is highly soluble in water and has a salty taste. In the body, potassium chloride plays a crucial role in maintaining fluid and electrolyte balance, nerve function, and muscle contraction.

Medically, potassium chloride is commonly used to treat or prevent low potassium levels (hypokalemia) in the blood. Hypokalemia can occur due to various reasons such as certain medications, kidney diseases, vomiting, diarrhea, or excessive sweating. Potassium chloride is available in various forms, including tablets, capsules, and liquids, and it's usually taken by mouth.

It's important to note that potassium chloride should be used with caution and under the supervision of a healthcare provider, as high levels of potassium (hyperkalemia) can be harmful and even life-threatening. Hyperkalemia can cause symptoms such as muscle weakness, irregular heartbeat, and cardiac arrest.

Delayed rectifier potassium channels are a type of ion channel found in the membrane of excitable cells, such as nerve and muscle cells. They are called "delayed rectifiers" because they activate and allow the flow of potassium ions (K+) out of the cell after a short delay following an action potential, or electrical signal.

These channels play a crucial role in regulating the duration and frequency of action potentials, helping to restore the resting membrane potential of the cell after it has fired. By allowing K+ to flow out of the cell, delayed rectifier potassium channels help to repolarize the membrane and bring it back to its resting state.

There are several different types of delayed rectifier potassium channels, which are classified based on their biophysical and pharmacological properties. These channels are important targets for drugs used to treat a variety of conditions, including cardiac arrhythmias, epilepsy, and psychiatric disorders.

The superior mesenteric artery (SMA) is a major artery that supplies oxygenated blood to the intestines, specifically the lower part of the duodenum, jejunum, ileum, cecum, ascending colon, and the first and second parts of the transverse colon. It originates from the abdominal aorta, located just inferior to the pancreas, and passes behind the neck of the pancreas before dividing into several branches to supply the intestines. The SMA is an essential vessel in the digestive system, providing blood flow for nutrient absorption and overall gut function.

Cyclic guanosine monophosphate (cGMP) is a important second messenger molecule that plays a crucial role in various biological processes within the human body. It is synthesized from guanosine triphosphate (GTP) by the enzyme guanylyl cyclase.

Cyclic GMP is involved in regulating diverse physiological functions, such as smooth muscle relaxation, cardiovascular function, and neurotransmission. It also plays a role in modulating immune responses and cellular growth and differentiation.

In the medical field, changes in cGMP levels or dysregulation of cGMP-dependent pathways have been implicated in various disease states, including pulmonary hypertension, heart failure, erectile dysfunction, and glaucoma. Therefore, pharmacological agents that target cGMP signaling are being developed as potential therapeutic options for these conditions.

Pinacidil is not typically defined in a medical dictionary as it is a specific pharmaceutical compound, rather than a general medical term. However, I can provide you with information about what Pinacidil is.

Pinacidil is an oral antihypertensive medication that acts as a direct activator of ATP-sensitive potassium (KATP) channels. These channels are present in various tissues, including the pancreas, heart, and smooth muscle cells. By opening KATP channels, Pinacidil causes hyperpolarization of the cell membrane, which leads to relaxation of smooth muscles in blood vessels. This results in vasodilation and a decrease in blood pressure.

Pinacidil is used off-label for the treatment of pulmonary arterial hypertension (PAH) due to its ability to dilate pulmonary arteries. However, it is not commonly prescribed for this purpose due to the availability of other FDA-approved medications specifically designed for PAH treatment.

Please consult a healthcare professional or pharmacist for more detailed information about Pinacidil and its uses, side effects, and potential interactions with other medications.

8,11,14-Eicosatrienoic acid is a type of fatty acid that contains 20 carbon atoms and three double bonds. The locations of these double bonds are at the 8th, 11th, and 14th carbon atoms, hence the name of the fatty acid. It is an omega-3 fatty acid, which means that the first double bond is located between the third and fourth carbon atoms from the methyl end of the molecule.

This particular fatty acid is not considered to be essential for human health, as it can be synthesized in the body from other fatty acids. It is a component of certain types of lipids found in animal tissues, including beef and lamb. It has been studied for its potential role in various physiological processes, such as inflammation and immune function, but its specific functions and effects on human health are not well understood.

Phenylephrine is a medication that belongs to the class of drugs known as sympathomimetic amines. It primarily acts as an alpha-1 adrenergic receptor agonist, which means it stimulates these receptors, leading to vasoconstriction (constriction of blood vessels). This effect can be useful in various medical situations, such as:

1. Nasal decongestion: When applied topically in the nose, phenylephrine causes constriction of the blood vessels in the nasal passages, which helps to relieve congestion and swelling. It is often found in over-the-counter (OTC) cold and allergy products.
2. Ocular circulation: In ophthalmology, phenylephrine is used to dilate the pupils before eye examinations. The increased pressure from vasoconstriction helps to open up the pupil, allowing for a better view of the internal structures of the eye.
3. Hypotension management: In some cases, phenylephrine may be given intravenously to treat low blood pressure (hypotension) during medical procedures like spinal anesthesia or septic shock. The vasoconstriction helps to increase blood pressure and improve perfusion of vital organs.

It is essential to use phenylephrine as directed, as improper usage can lead to adverse effects such as increased heart rate, hypertension, arrhythmias, and rebound congestion (when used as a nasal decongestant). Always consult with a healthcare professional for appropriate guidance on using this medication.

Synaptosomes are subcellular structures that can be isolated from the brain tissue. They are formed during the fractionation process of brain homogenates and consist of intact presynaptic terminals, including the synaptic vesicles, mitochondria, and cytoskeletal elements. Synaptosomes are often used in neuroscience research to study the biochemical properties and functions of neuronal synapses, such as neurotransmitter release, uptake, and metabolism.

A microelectrode is a small electrode with dimensions ranging from several micrometers to a few tens of micrometers in diameter. They are used in various biomedical applications, such as neurophysiological studies, neuromodulation, and brain-computer interfaces. In these applications, microelectrodes serve to record electrical activity from individual or small groups of neurons or deliver electrical stimuli to specific neural structures with high spatial resolution.

Microelectrodes can be fabricated using various materials, including metals (e.g., tungsten, stainless steel, platinum), metal alloys, carbon fibers, and semiconductor materials like silicon. The design of microelectrodes may vary depending on the specific application, with some common types being sharpened metal wires, glass-insulated metal microwires, and silicon-based probes with multiple recording sites.

The development and use of microelectrodes have significantly contributed to our understanding of neural function in health and disease, enabling researchers and clinicians to investigate the underlying mechanisms of neurological disorders and develop novel therapies for conditions such as Parkinson's disease, epilepsy, and hearing loss.

Cyclooxygenase (COX) inhibitors are a class of drugs that work by blocking the activity of cyclooxygenase enzymes, which are involved in the production of prostaglandins. Prostaglandins are hormone-like substances that play a role in inflammation, pain, and fever.

There are two main types of COX enzymes: COX-1 and COX-2. COX-1 is produced continuously in various tissues throughout the body and helps maintain the normal function of the stomach and kidneys, among other things. COX-2, on the other hand, is produced in response to inflammation and is involved in the production of prostaglandins that contribute to pain, fever, and inflammation.

COX inhibitors can be non-selective, meaning they block both COX-1 and COX-2, or selective, meaning they primarily block COX-2. Non-selective COX inhibitors include drugs such as aspirin, ibuprofen, and naproxen, while selective COX inhibitors are often referred to as coxibs and include celecoxib (Celebrex) and rofecoxib (Vioxx).

COX inhibitors are commonly used to treat pain, inflammation, and fever. However, long-term use of non-selective COX inhibitors can increase the risk of gastrointestinal side effects such as ulcers and bleeding, while selective COX inhibitors may be associated with an increased risk of cardiovascular events such as heart attack and stroke. It is important to talk to a healthcare provider about the potential risks and benefits of COX inhibitors before using them.

Vasoconstrictor agents are substances that cause the narrowing of blood vessels by constricting the smooth muscle in their walls. This leads to an increase in blood pressure and a decrease in blood flow. They work by activating the sympathetic nervous system, which triggers the release of neurotransmitters such as norepinephrine and epinephrine that bind to alpha-adrenergic receptors on the smooth muscle cells of the blood vessel walls, causing them to contract.

Vasoconstrictor agents are used medically for a variety of purposes, including:

* Treating hypotension (low blood pressure)
* Controlling bleeding during surgery or childbirth
* Relieving symptoms of nasal congestion in conditions such as the common cold or allergies

Examples of vasoconstrictor agents include phenylephrine, oxymetazoline, and epinephrine. It's important to note that prolonged use or excessive doses of vasoconstrictor agents can lead to rebound congestion and other adverse effects, so they should be used with caution and under the guidance of a healthcare professional.

The trachea, also known as the windpipe, is a tube-like structure in the respiratory system that connects the larynx (voice box) to the bronchi (the two branches leading to each lung). It is composed of several incomplete rings of cartilage and smooth muscle, which provide support and flexibility. The trachea plays a crucial role in directing incoming air to the lungs during inspiration and outgoing air to the larynx during expiration.

Benzimidazoles are a class of heterocyclic compounds containing a benzene fused to a imidazole ring. They have a wide range of pharmacological activities and are used in the treatment of various diseases. Some of the benzimidazoles are used as antiparasitics, such as albendazole and mebendazole, which are effective against a variety of worm infestations. Other benzimidazoles have antifungal properties, such as thiabendazole and fuberidazole, and are used to treat fungal infections. Additionally, some benzimidazoles have been found to have anti-cancer properties and are being investigated for their potential use in cancer therapy.

Sprague-Dawley rats are a strain of albino laboratory rats that are widely used in scientific research. They were first developed by researchers H.H. Sprague and R.C. Dawley in the early 20th century, and have since become one of the most commonly used rat strains in biomedical research due to their relatively large size, ease of handling, and consistent genetic background.

Sprague-Dawley rats are outbred, which means that they are genetically diverse and do not suffer from the same limitations as inbred strains, which can have reduced fertility and increased susceptibility to certain diseases. They are also characterized by their docile nature and low levels of aggression, making them easier to handle and study than some other rat strains.

These rats are used in a wide variety of research areas, including toxicology, pharmacology, nutrition, cancer, and behavioral studies. Because they are genetically diverse, Sprague-Dawley rats can be used to model a range of human diseases and conditions, making them an important tool in the development of new drugs and therapies.

Coronary vessels refer to the network of blood vessels that supply oxygenated blood and nutrients to the heart muscle, also known as the myocardium. The two main coronary arteries are the left main coronary artery and the right coronary artery.

The left main coronary artery branches off into the left anterior descending artery (LAD) and the left circumflex artery (LCx). The LAD supplies blood to the front of the heart, while the LCx supplies blood to the side and back of the heart.

The right coronary artery supplies blood to the right lower part of the heart, including the right atrium and ventricle, as well as the back of the heart.

Coronary vessel disease (CVD) occurs when these vessels become narrowed or blocked due to the buildup of plaque, leading to reduced blood flow to the heart muscle. This can result in chest pain, shortness of breath, or a heart attack.

... contains three disulfide bridges. Charybdotoxin occludes the pore of calcium-activated voltage-gated shaker K+ ... The Charybdotoxin family of scorpion toxins is a group of small peptides that has many family members, such as the pandinotoxin ... Charybdotoxin, a 37 amino acid, 4 kDa neurotoxin with the molecular formula C176H277N57O55S7, is one of the peptide toxins that ... Charybdotoxin (ChTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus ( ...
The amino terminal region of Pi3 lacks three residues when compared to other toxins of the same family e.g. charybdotoxin. ... The three-dimensional structure of Pi3 is similar to other potassium channel blocking toxins like charybdotoxin, because it has ... Miller C (July 1995). "The charybdotoxin family of K+ channel-blocking peptides". Neuron. 15 (1): 5-10. doi:10.1016/0896-6273( ...
Miller C (July 1995). "The charybdotoxin family of K+ channel-blocking peptides". Neuron. 15 (1): 5-10. doi:10.1016/0896-6273( ...
Bontems F, Roumestand C, Gilquin B, Ménez A, Toma F (December 1991). "Refined structure of charybdotoxin: common motifs in ... Gao YD, Garcia ML (August 2003). "Interaction of agitoxin2, charybdotoxin, and iberiotoxin with potassium channels: selectivity ... Gao YD, Garcia ML (August 2003). "Interaction of agitoxin2, charybdotoxin, and iberiotoxin with potassium channels: selectivity ... Other toxins found in this species include charybdotoxin (CTX). CTX is a close homologue of Agitoxin. Agitoxin can be purified ...
Goldstein, S.A.; Miller, C. (1993). "Mechanism of charybdotoxin block of a voltage-gated K+ channel". Biophysical Journal. 65 ( ... Park, Chul-Seung; Miller, Christopher (1992). "Interaction of charybdotoxin with permeant ions inside the pore of a K+ channel ...
Miller C. The charybdotoxin family of K+ channel-blocking peptides. Neuron 1995;15(1-5). (Ion channel toxins, Peptides). ...
Theoretical predictions and experimental results with charybdotoxin and phospholipid vesicles". Biophysical Journal. 73 (4): ... charybdotoxin or hisactophilin. Orientations and penetration depths of many amphitropic proteins and peptides in membranes are ... cationic toxins such as charybdotoxin, and specific membrane-targeting domains such as some PH domains, C1 domains, and C2 ...
Naranjo D, Miller C (January 1996). "A strongly interacting pair of residues on the contact surface of charybdotoxin and a ... Examples of calcium-activated potassium channel blockers include: Charybdotoxin Iberiotoxin Apamin Kaliotoxin, Lolitrem, BKCa- ... "Electrostatic interaction between charybdotoxin and a tetrameric mutant of Shaker K(+) channels". Biophysical Journal. 78 (5): ...
NTX is similar in sequence to the margatoxin (79% identity), the kaliotoxin (51% identity), the charybdotoxin (49% identity), ... "Charybdotoxin and noxiustoxin, two homologous peptide inhibitors of the K+(Ca2+) channel". FEBS Letters. 226 (2): 280-284. doi: ...
Naranjo D, Miller C (January 1996). "A strongly interacting pair of residues on the contact surface of charybdotoxin and a ... ISBN 978-0-443-07145-4. Thompson J, Begenisich T (May 2000). "Electrostatic interaction between charybdotoxin and a tetrameric ...
Miller C (December 1988). "Competition for block of a Ca2(+)-activated K+ channel by charybdotoxin and tetraethylammonium". ...
The poison from this scorpion contain 4 components: chlorotoxin, charybdotoxin, scyllatoxin, and agitoxins. Upon injection with ...
LbTX displays 57% sequence homology with charybdotoxin and 70% sequence homology with iberiotoxin. LbTX contains a β-sheet ...
The poison from this scorpion contain 4 components: chlorotoxin, charybdotoxin, scyllatoxin, and agitoxins. Upon injection with ...
Charybdotoxin Luo L, Li B, Wang S, Wu F, Wang X, Liang P, et al. (February 2018). "Centipedes subdue giant prey by blocking ...
Neurotoxins in L. quinquestriatus venom include: Chlorotoxin Charybdotoxin, a blocker of calcium-activated potassium channels. ...
The complete amino acid sequence has been defined and it displays 68% sequence homology with charybdotoxin. Iberiotoxin binds ...
In this state BK channels can still be inhibited by one of their inhibitors, like charybdotoxin (CTX). Opening of the BK ...
The 37 amino acid peptide belongs to the charybdotoxin sub-family (αKTx1) and was numbered member 11. αKTx1.11 revealed ...
... is also known as Potassium channel toxin alpha-KTx 1.2, Charybdotoxin-2, ChTX-Lq2, ChTx-d, Toxin 18-2 or Lqh 18-2. The name ... Lq2 contains the classical scorpion toxin alpha-beta scaffold and is structurally similar to the neurotoxin Charybdotoxin (CTX ...
... mechanism of the antiproliferative effect of charybdotoxin". Proceedings of the National Academy of Sciences of the United ...
... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proc. Natl. Acad. Sci. U.S.A. 97 (10): 5562-7. ...
... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proc. Natl. Acad. Sci. U.S.A. 97 (10): 5562-7. ...
... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proceedings of the National Academy of Sciences of ...
The sequence has a large homology with iberiotoxin from Buthus tumulus, charybdotoxin from Leiurus quinquestriatus and ...
... similarity of sapecin B to charybdotoxin". The Biochemical Journal. 291 ( Pt 1) (Pt 1): 275-9. doi:10.1042/bj2910275. PMC ...
... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proc. Natl. Acad. Sci. U.S.A. 97 (10): 5562-7. ...
Charybdotoxin is also found in the venom from the same species of scorpion, and is named after the sea monster Charybdis. In ...
This suggests that TmTx does not have an effect on SK channels or charybdotoxin-sensitive IK channels (calcium-activated ...
Neurotoxins in L. quinquestriatus venom include: Chlorotoxin Charybdotoxin Scyllatoxin Agitoxins types one, two and three The ...
Charybdotoxin contains three disulfide bridges. Charybdotoxin occludes the pore of calcium-activated voltage-gated shaker K+ ... The Charybdotoxin family of scorpion toxins is a group of small peptides that has many family members, such as the pandinotoxin ... Charybdotoxin, a 37 amino acid, 4 kDa neurotoxin with the molecular formula C176H277N57O55S7, is one of the peptide toxins that ... Charybdotoxin (ChTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus ( ...
Charybdotoxin. Empirical Formula (Hill Notation). : C176H277N57O55S7. CAS No.. : 95751-30-7. Molecular Weight. : 4295.89. ...
charybdotoxin. TTX. tetrodotoxin. EGTA. ethylene glycol bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid. HEPES. 4-(2- ... 1995) Charybdotoxin and its effects on potassium channels. Am J Physiol 269:C1-C10. ...
Charybdotoxin. C176H277N57O55S7. ...
MacKinnon R, Miller C. Mechanism of charybdotoxin block of the high-conductance, Ca2+-activated K+ channel. J Gen Physiol. 1988 ...
Blockade of BKi current by charybdotoxin abolishes this behavior, showing that afterhyperpolarizations mediated by BKi current ...
Ba,sup,2+,/sup, was also without effect in the presence of either apamin or charybdotoxin. 5. In contrast to EDHF, an increase ... Ba2+ was also without effect in the presence of either apamin or charybdotoxin. 5. In contrast to EDHF, an increase in ... partially inhibited EDHF relaxations when each of them was combined with charybdotoxin (300 nM). 2. The IK(Ca) inhibitors ... partially inhibited EDHF relaxations when each of them was combined with charybdotoxin (300 nM). 2. The IK(Ca) inhibitors ...
Crystal structure of Kv1.2-2.1 paddle chimera channel in complex with Lys27Met mutant of Charybdotoxin. ... Crystal structure of Kv1.2-2.1 paddle chimera channel in complex with Charybdotoxin in Cs+. ... Crystal structure of Kv1.2-2.1 paddle chimera channel in complex with Charybdotoxin. ...
Responses to Hb-200 were unaffected by incubation with charybdotoxin and apamin, BQ-788, or superoxide dismutase.,p,,/p, ... charybdotoxin and apamin), an endothelin antagonist (BQ-788) and the antioxidant superoxide dismutase.,p,,/p, RESULTS: ...
Verheugen JA, Korn H. A charybdotoxin-insensitive conductance in human T lymphocytes: T cell membrane potential is set by ...
What makes this small scorpion so dangerous? Its venom is a mix of neurotoxins - chlorotoxin, charybdotoxin, scyllatoxin, and ...
Many cases of serotonin toxicity occur in people who have ingested drug combinations that synergistically increase synaptic serotonin.[10] It may also occur due to an overdose of a single serotonergic agent.[27] The combination of monoamine oxidase inhibitors (MAOIs) with precursors such as L-tryptophan or 5-hydroxytryptophan pose a particularly acute risk of life-threatening serotonin syndrome.[28] The case of combination of MAOIs with tryptamine agonists (commonly known as ayahuasca) can present similar dangers as their combination with precursors, but this phenomenon has been described in general terms as the cheese effect. Many MAOIs irreversibly inhibit monoamine oxidase. It can take at least four weeks for this enzyme to be replaced by the body in the instance of irreversible inhibitors.[29] With respect to tricyclic antidepressants, only clomipramine and imipramine have a risk of causing SS.[30] Many medications may have been incorrectly thought to cause SS. For example, some case reports ...
Toxins are often distinguished from other chemical agents strictly based on their biological origin.[7] Less strict understandings embrace naturally occurring non-organic toxins, such as arsenic.[8][9][10] Other understandings embrace synthetic analogs of naturally occurring organic poisons as toxins,[11] and may[12] or may not[13] embrace naturally occurring non-organic poisons. It is important to confirm usage if a common understanding is critical. Toxins are a subset of toxicants. The term toxicant is preferred when the poison is man-made and therefore artificial.[14] The human and scientific genetic assembly of a natural-based toxin should be considered a toxin as it is identical to its natural counterpart.[15] The debate is one of linguistic semantics. The word toxin does not specify method of delivery (as opposed to venom, a toxin delivered via a bite, sting, etc.). Poison is a related but broader term that encompasses both toxins and toxicants; poisons may enter the body through any means ...
keywords = "angiotensin II, atrial natriuretic peptide, charybdotoxin, guanosine 3,5-cyclic monophosphate, guanylyl cyclase, ...
Charybdotoxin. Glp-Phe-Thr-Asn-Val-Ser-Cys-Thr-Thr-Ser-Lys-Glu-Cys-Trp-Ser-Val-Cys-Gln-Arg-Leu-His-Asn-Thr-Ser-Arg-Gly-Lys-Cys- ...
... or charybdotoxin (ChTX; 50 nM; pEC50=6.3+/-0.2; n=4), a peptide blocker of large conductance, calcium-activated potassium ... or charybdotoxin (ChTX; 50 nM; pEC50=6.3+/-0.2; n=4), a peptide blocker of large conductance, calcium-activated potassium ...
... charybdotoxin (ChTX) (scorpion, Leiurus quinquestriatus var. hebraeus); chlorotoxin; conotoxin GI (marine snail, Conus ...
Other toxins found in this species include charybdotoxin (CTX). CTX is a close homologue of Agitoxin. ...
KAX1C_LEIHE Potassium channel toxin alpha-KTx 1.12 (Charybdotoxin b) ... Short scorpion toxin ... ... KAX1D_LEIHE Potassium channel toxin alpha-KTx 1.13 (Charybdotoxin c) ... Short scorpion toxin ... ...
... channels with charybdotoxin (CTX). Furthermore, pretreatment with either fAβ(1-42) or sAβ(1-42) induced microglial priming, ...
Goldstein, S.A.; Miller, C. Mechanism of charybdotoxin block of a voltage-gated K+ channel. Biophys. J. 1993, 65, 1613-1619. [ ... charybdotoxin [11] and noxiustoxin [12], and others can even reach the picomolar range, e.g., Vm24 [13], ShK [14], margatoxin [ ...
charybdotoxin). Charybdotoxin enhanced its ability to prevent K+ current of BK(α + ß4 H101Y) channel. The charybdotoxin Q18F ... Development of charybdotoxin Q18F variant as a selective peptide blocker of neuronal BK(α + ß4) channel for the treatment of ... Charybdotoxin is a non-specific inhibitor of BK and other K+ channels. Here, by nuclear magnetic resonance (NMR) and other ... These results implied that charybdotoxin Q18F variant could be potentially used for intractable epilepsy treatment by ...
Ba2+ was also without impact in the current presence of either apamin or charybdotoxin. As opposed to EDHF, a… Continue reading ... partially inhibited EDHF relaxations when all of them was coupled with charybdotoxin (300?nM). mixture inhibited EDHF ...
5. Exposure of intact arterial segments to charybdotoxin and apamin, in the presence of NO synthase blockers, also ... charybdotoxin did significantly inhibit SIN-1-evoked relaxation to a similar extent as intact tissues (maximum response induced ... relaxation to SIN-1 was not reduced in the presence of charybdotoxin (n = 6; P , 0.05). However, in the presence of NO synthase ... but did not alter the effects of charybdotoxin and ODQ and SIN-1-evoked relaxation. 7. These data show that although relaxation ...
... may be blocked by iberiotoxin and charybdotoxin (Ch Tx), and are found in red and white blood cells, colon, lung, pancreas, and ...
d.m.) Index durum Charybdotoxin web Sample Results indicate mean values of Saragolla_LA 83.four d.m. = dry matter. 10.two 12.7 ...
"Nitric Oxide and CGMP Cause Vasorelaxation by Activation of a Charybdotoxin-Sensitive K Channel by CGMP-Dependent Protein ...
  • Ba 2+ was also without effect in the presence of either apamin or charybdotoxin. (lu.se)
  • Responses were further studied in the presence or absence of the endothelium, inhibitors of endothelium-dependent vasodilation (L-NAME, charybdotoxin and apamin), an endothelin antagonist (BQ-788) and the antioxidant superoxide dismutase. (gla.ac.uk)
  • Responses to Hb-200 were unaffected by incubation with charybdotoxin and apamin, BQ-788, or superoxide dismutase. (gla.ac.uk)
  • Ba2+ was also without impact in the current presence of either apamin or charybdotoxin. (cell-metabolism.com)
  • Combined application of apamin and charybdotoxin blocked EDHF responses, revealing the critical role of these channels as iberiotoxin was unable to substitute for charybdotoxin. (ox.ac.uk)
  • Intermediate (IK) channels, on the other hand, have conductances of 11- 40 pS, are voltage-independent, may be blocked by iberiotoxin and charybdotoxin (Ch Tx), and are found in red and white blood cells, colon, lung, pancreas, and other tissues. (conicyt.cl)
  • Association of the subunit with numerous subunits modulates channel properties, including kinetic behavior, voltage dependence, calcium level of sensitivity, and pharmacological attributes such as sensitivity to the channel blockers, iberiotoxin and charybdotoxin (Dworetzky et al. (health-e-nc.org)
  • 1. In the rat hepatic artery, the SK(Ca) inhibitors UCL 1684 (300 nM) completely blocked, and scyllatoxin (1 μM) and d-tubocurarine (100 μM) partially inhibited EDHF relaxations when each of them was combined with charybdotoxin (300 nM). (lu.se)
  • Charybdotoxin (ChTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus (deathstalker) that blocks calcium-activated potassium channels. (wikipedia.org)
  • The Charybdotoxin family of scorpion toxins is a group of small peptides that has many family members, such as the pandinotoxin, derived from the venom of scorpion Pandinus imperator. (wikipedia.org)
  • Charybdotoxin, a 37 amino acid, 4 kDa neurotoxin with the molecular formula C176H277N57O55S7, is one of the peptide toxins that can be extracted from the venom of the scorpion. (wikipedia.org)
  • The blockade of K+ channels by the charybdotoxin peptide causes neuronal hyperexcitability. (wikipedia.org)
  • Blockade of BKi current by charybdotoxin abolishes this behavior, showing that afterhyperpolarizations mediated by BKi current are permissive for repetitive firing. (jneurosci.org)
  • In contrast, when basal NO synthesis is inhibited, SIN-1 appears to cause full relaxation by both the activation of a charybdotoxin-sensitive pathway and the stimulation of soluble guanylyl cyclase. (ox.ac.uk)
  • 30 u ml-1), potentiated relaxations to SIN-1 in all tissues, but did not alter the effects of charybdotoxin and ODQ and SIN-1-evoked relaxation. (ox.ac.uk)
  • Index durum Charybdotoxin web Sample Results indicate mean values of Saragolla_LA 83.four d.m. = dry matter. (gsk-3inhibitor.com)
  • Charybdotoxin occludes the pore of calcium-activated voltage-gated shaker K+ channels by binding to one of four independent, overlapping binding sites. (wikipedia.org)
  • The Charybdotoxin family of scorpion toxins is a group of small peptides that has many family members, such as the pandinotoxin, derived from the venom of scorpion Pandinus imperator. (wikipedia.org)
  • Charybdotoxin, a 37 amino acid, 4 kDa neurotoxin with the molecular formula C176H277N57O55S7, is one of the peptide toxins that can be extracted from the venom of the scorpion. (wikipedia.org)
  • In oocytes, iberiotoxin and charybdotoxin, peptidyl scorpion toxins, were both equally effective blockers of BK current, although iberiotoxin was significantly more potent than charybdotoxin. (aspetjournals.org)
  • The blockade of K+ channels by the charybdotoxin peptide causes neuronal hyperexcitability. (wikipedia.org)
  • The biological activity of Charybdotoxin is examined by the Division of Pharmacology, Peptide Institute, Inc. (peptanova.de)
  • Charybdotoxin is a potent neurotoxin isolated from the deathstalker scorpion, Leiurus quinquestriatus hebraeus . (echelon-inc.com)
  • studies with charybdotoxin and tetraethylammonium indicate that a Ca2(+)-sensitive K+ channel (K(Ca] appears to be involved. (nih.gov)
  • Inside the present study, pediatric cardiologists have been currently content material using the 3D virtual models, whereas surgeons and also the operative group facing the Charybdotoxin custom synthesis context of rising complexity still essential the added demonstrating value of 3D-printed models. (gpr44.com)
  • Charybdotoxin is a highly efficient ion channel blocker with effects on mitogen-induced proliferationon of peripheral T lymphocytes. (peptanova.de)
  • 3. Impairment of brain mitochondrial charybdotoxin- and ATP-insensitive BK channel activities in diabetes. (nih.gov)
  • Makes KCNMA1 channel resistant to 100 nM charybdotoxin (CTX) toxin concentrations. (nih.gov)
  • In the present behavioral experiments, we investigated the effects of the BK channel antagonist charybdotoxin(CTX)and the NR2B subunit antagonist ifenprodil(IFN)on a nociceptive behavior in peripheral-nerve-injured mice. (nii.ac.jp)