Charybdotoxin. Medical search

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)

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.

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.

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)

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( ...

https://en.wikipedia.org/wiki/Pandinus_imperator_(Pi3)_toxin

Miller C (July 1995). "The charybdotoxin family of K+ channel-blocking peptides". Neuron. 15 (1): 5-10. doi:10.1016/0896-6273( ...

https://en.wikipedia.org/wiki/Scorpion_toxin

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 ...

https://en.wikipedia.org/wiki/Agitoxin

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 ...

https://en.wikipedia.org/wiki/Pandinus_imperator_toxin_(Pi4)

Miller C. The charybdotoxin family of K+ channel-blocking peptides. Neuron 1995;15(1-5).. ...

https://en.wikipedia.org/wiki/Pi5

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 ...

https://en.wikipedia.org/wiki/Peripheral_membrane_protein

Naranjo D, Miller C (January 1996). "A strongly interacting pair of residues on the contact surface of charybdotoxin and a ... Examples of calcium-activated channel blockers include: Charybdotoxin Iberiotoxin Apamin Kaliotoxin, Lolitrem, BKCa-specific ... "Electrostatic interaction between charybdotoxin and a tetrameric mutant of Shaker K(+) channels". Biophysical Journal. 78 (5): ...

https://en.wikipedia.org/wiki/Potassium_channel_blocker

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: ...

https://en.wikipedia.org/wiki/Noxiustoxin

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 ...

https://en.wikipedia.org/wiki/Potassium_channel

Miller C (December 1988). "Competition for block of a Ca2(+)-activated K+ channel by charybdotoxin and tetraethylammonium". ...

https://en.wikipedia.org/wiki/Channel_blocker

The poison from this scorpion contain 4 components: chlorotoxin, charybdotoxin, scyllatoxin, and agitoxins. Upon injection with ...

https://en.wikipedia.org/wiki/Scorpionism_in_Central_America

LbTX displays 57% sequence homology with charybdotoxin and 70% sequence homology with iberiotoxin. LbTX contains a β-sheet ...

https://en.wikipedia.org/wiki/Limbatustoxin

Charybdotoxin Luo L, Li B, Wang S, Wu F, Wang X, Liang P, et al. (February 2018). "Centipedes subdue giant prey by blocking ...

https://en.wikipedia.org/wiki/Ssm_spooky_toxin

The complete amino acid sequence has been defined and it displays 68% sequence homology with charybdotoxin. Iberiotoxin binds ...

https://en.wikipedia.org/wiki/Iberiotoxin

In this state BK channels can still be inhibited by one of their inhibitors, like charybdotoxin (CTX). Opening of the BK ...

https://en.wikipedia.org/wiki/Isopimaric_acid

The 37 amino acid peptide belongs to the charybdotoxin sub-family (αKTx1) and was numbered member 11. αKTx1.11 revealed ...

https://en.wikipedia.org/wiki/Slotoxin

... 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 ...

https://en.wikipedia.org/wiki/Lq2

... mechanism of the antiproliferative effect of charybdotoxin". Proceedings of the National Academy of Sciences of the United ...

https://en.wikipedia.org/wiki/Stichodactyla_toxin

... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proc. Natl. Acad. Sci. U.S.A. 97 (10): 5562-7. doi: ...

https://en.wikipedia.org/wiki/KCNMB2

... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin". Proceedings of the National Academy of Sciences of ...

https://en.wikipedia.org/wiki/KCNMB1

The sequence has a large homology with iberiotoxin from Buthus tumulus, charybdotoxin from Leiurus quinquestriatus and ...

https://en.wikipedia.org/wiki/Kaliotoxin

... similarity of sapecin B to charybdotoxin". The Biochemical Journal. 291 ( Pt 1): 275-9. doi:10.1042/bj2910275. PMC 1132513. ...

https://en.wikipedia.org/wiki/Arthropod_defensin

Charybdotoxin is also found in the venom from the same species of scorpion, and is named after the sea monster Charybdis. In ...

https://en.wikipedia.org/wiki/Scyllatoxin

This suggests that TmTx does not have an effect on SK channels or charybdotoxin-sensitive IK channels (calcium-activated ...

https://en.wikipedia.org/wiki/Tamulotoxin

Neurotoxins in L. quinquestriatus venom include: Chlorotoxin Charybdotoxin Scyllatoxin Agitoxins types one, two and three The ...

https://en.wikipedia.org/wiki/Deathstalker

... face of the α-helix is anchored to the β-sheet by three disulfide bonds which are conserved in all members of the charybdotoxin ...

https://en.wikipedia.org/wiki/Pandinotoxin

... charybdotoxin, noxiustoxin, anuroctoxin, OdK2) and sea anemone (ShK, ShK-F6CA, ShK-186, ShK-192, BgK), and by small molecule ...

https://en.wikipedia.org/wiki/KCNA3

... a genetic disorder Charybdotoxin, a toxin found in scorpion venom Chemotherapy, treatment of cancer with cytotoxic drugs ...

https://en.wikipedia.org/wiki/CTX

... charybdotoxin MeSH D20.888.065.870 - spider venoms MeSH D20.888.065.870.650 - omega-agatoxin iva MeSH D20.888.065.970 - wasp ...

https://en.wikipedia.org/wiki/List_of_MeSH_codes_(D20)

... and the scorpion venoms tamapin and charybdotoxin (ChTx), all via competitive antagonism for access to the mouth of the pore ...

https://en.wikipedia.org/wiki/SK_channel

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 (CTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus (deathstalker ...

https://en.wikipedia.org/wiki/Charybdotoxin

Charybdotoxin (ChTX), a K+ channel blocker, depolarizes human peripheral T lymphocytes and renders them insensitive to ... mechanism of the antiproliferative effect of charybdotoxin. R J Leonard, M L Garcia, R S Slaughter, and J P Reuben ... mechanism of the antiproliferative effect of charybdotoxin ... mechanism of the antiproliferative effect of charybdotoxin. R J ... mechanism of the antiproliferative effect of charybdotoxin ...

https://www.pnas.org/content/89/21/10094?ijkey=a8fbe21296d7cd1618b16891ae6e0ea1d36eb263&keytype2=tf_ipsecsha

Molecular Structure of Charybdotoxin: Retraction. By WALTER MASSEFSKI JR., ALFRED G. REDFIELD, DENNIS R. HARE, CHRISTOPHER ... Molecular Structure of Charybdotoxin: Retraction. By WALTER MASSEFSKI JR., ALFRED G. REDFIELD, DENNIS R. HARE, CHRISTOPHER ... Molecular Structure of Charybdotoxin: Retraction. By WALTER MASSEFSKI JR., ALFRED G. REDFIELD, DENNIS R. HARE, CHRISTOPHER ...

https://science.sciencemag.org/content/252/5006/631.2

charybdotoxin-GLU32 analog ligand page. Quantitative data and detailed annnotation of the targets of licensed and experimental ...

http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=2329

... ... and charybdotoxin (CTX) and to gain new insights into the molecular determinants that define the interaction of these pore- ...

https://insights.ovid.com/toxic/200406150/00007824-200406150-00013

Charybdotoxin and two N-terminal truncated peptides, corresponding to the 2-37 and 7-37 sequences, were obtained by stepwise ... Synthesis of charybdotoxin and of two N-terminal truncated analogues. Structural and functional characterisation ... We conclude that the N-terminal region of charybdotoxin plays a functional role in tuning the toxins biological activity but ... NMR data show that synthetic charybdotoxin is indistinguishable from the natural protein. The two truncated proteins contain ...

https://strathprints.strath.ac.uk/31666/

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https://www.infona.pl/resource/bwmeta1.element.acs-doi-10_1021_bi051656d

Buy Charybdotoxin - an affordable, high quality KCa channel inhibitor from Hello Bio, a trusted supplier for life science ... References for Charybdotoxin. *. Purification, sequence, and model structure of charybdotoxin, a potent selective inhibitor of ... Electrostatic interaction between charybdotoxin and a tetrameric mutant of Shaker K(+) channels.. Thompson J et al (2000) ... Charybdotoxin and margatoxin acting on the human voltage-gated potassium channel hKv1.3 and its H399N mutant: an experimental ...

https://www.hellobio.com/charybdotoxin.html

Charybdotoxin Binding in the IKs Pore Demonstrates Two MinK Subunits in Each Channel Complex. Haijun Chen, Leo A. Kim, Sindhu K ... Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian skeletal muscle. @article{ ... Miller1985CharybdotoxinAP, title={Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian ...

https://www.semanticscholar.org/paper/Charybdotoxin%2C-a-protein-inhibitor-of-single-K%2B-Miller-Moczydlowski/ce46a94f5ee23f7ca7b8d6c19a525037c95d632c

"Charybdotoxin" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical Subject ... This graph shows the total number of publications written about "Charybdotoxin" by people in this website by year, and whether ... Below are the most recent publications written about "Charybdotoxin" by people in Profiles. ...

https://researchers.childrensmercy.org/display/20391

Charybdotoxin - SBP0166 - Charybdotoxin MW: 4295.95 pGlu-Phe-Thr-Asn-Val-Ser-Cys-Thr-Thr-Ser-Lys-Glu-Cys-Trp-Ser-Val-Cys-Gln- ... SBP0166 - Charybdotoxin. MW: 4295.95. pGlu-Phe-Thr-Asn-Val-Ser-Cys-Thr-Thr-Ser-Lys-Glu-Cys-Trp-Ser-Val-Cys-Gln-Arg-Leu-His-Asn- ...

http://www.severnbiotech.com/index.php?main_page=product_info&cPath=109_151&products_id=669

Charybdotoxin. KCa2+ channel blocker. Charybdotoxin (ChTx) is a 37 amino acid peptide isolated from the venom of the scorpion ... Mechanism of charybdotoxin block of a voltage-gated K+ channel.. Charybdotoxin block of a Shaker K+ channel was studied in ... The charybdotoxin receptor of a Shaker K+ channel: peptide and channel residues mediating molecular recognition.. Charybdotoxin ... Charybdotoxin (ChTX), a protein present in the venom of the scorpion Leiurus quinquestriatus var. hebraeus, has been purified ...

https://www.smartox-biotech.com/product/kca-channels/charybdotoxin

Charybdotoxin (ChTX; 10 nM), which blocks large conductance Ca(2+)-activated K(+)-channel function, completely blocked and ...

https://www.pnas.org/content/89/4/1325

https://en.wikipedia.org/wiki/Pandinus_imperator_(Pi3)_toxin

... and was sensitive to block by external charybdotoxin or tetraethylammonium (TEA) and by internal Ba2+. At +60 mV it was ...

https://pubmed.ncbi.nlm.nih.gov/10420003/?dopt=Abstract

Charybdotoxin, an inhibitor of Ca++-activated K+ channels, reduced vasodilator responses to Ach without affecting those to ... Charybdotoxin, an inhibitor of Ca++-activated K+ channels, reduced vasodilator responses to Ach without affecting those to ... Charybdotoxin, an inhibitor of Ca++-activated K+ channels, reduced vasodilator responses to Ach without affecting those to ... Charybdotoxin, an inhibitor of Ca++-activated K+ channels, reduced vasodilator responses to Ach without affecting those to ...

https://augusta.pure.elsevier.com/en/publications/no-independent-vasodilation-to-acetylcholine-in-the-rat-isolated-

charybdotoxin. IbTX. iberiotoxin. MgTX. margatoxin. KTX. kaliotoxin. AgTX1. agitoxin-1. AgTX2. agitoxin-2. α-DaTX. α- ... but not by charybdotoxin, which blocks Kv1.2 and 1.3 but not 1.1. The data taken together suggest that high-affinity blockade ...

https://jpet.aspetjournals.org/content/289/3/1517

Indo, indomethacin; CTx, charybdotoxin; Apm, apamin. *, P , 0.05; **, P , 0.01. Relative contribution of EDHF in male (I) and ... and a combination of charybdotoxin and apamin, respectively (14, 21). To examine the effect of NOS uncoupling on EDHF-mediated ... but were markedly inhibited by a combination of 100 nM charybdotoxin (an inhibitor of large- and intermediate-conductance ...

http://jem.rupress.org/content/205/9/2053

A charybdotoxin-insensitive conductance in human T lymphocytes: T cell membrane potential is set by distinct K+ channels. J. ... Ca2+ induces charybdotoxin-sensitive membrane potential changes in rat lymphocytes. Am. J. Physiol. 257:C197-C206. ... Charybdotoxin (CTX)* and margatoxin (MgTX), which block the predominant voltage-dependent potassium (Kv) channel (Kv1.3) of ... charybdotoxin; DTX-I, dendrotoxin-I; DTX-K, dendrotoxin K; Kv channel, voltage-gated potassium channel; MgTX, margatoxin; Vm, ...

http://jem.rupress.org/content/196/7/897

The fluoranthene-induced modulations of these anion transporters were counteracted by charybdotoxin (ChTx, a hIK-1 channel ... charybdotoxin; DEP, diesel exhaust particle; DNDS, 4,4′-dinitrostilbene-2,2′-disulfonic acid; FLT, fluoranthene; ISO, ...

http://jpet.aspetjournals.org/content/308/2/651

Lack of Effect of Charybdotoxin on RPV KDR. Charybdotoxin was previously shown to block homomultimeric Kv1.2 channels27-29 but ... as well as a lack of sensitivity to charybdotoxin. Kv1.5 channels are not affected by charybdotoxin,28,29 but we found that RPV ... RPV KDR current was not affected by charybdotoxin block of Kv1.2 homotetramers27-29; however, we found that heteromultimeric ... Finally, native KDR current was found to be insensitive to charybdotoxin-block of homomultimeric Kv1.2 channels. The findings ...

http://circres.ahajournals.org/content/89/11/1038

Charybdotoxin (10(-7) M), an inhibitor of Ca(2+)-activated K+ channels, almost doubled [Ca2+]i, whereas glibenclamide (10(-5) M ... The average resting membrane potential (RMP) was -36 +/- 3 mV and could be depolarized by charybdotoxin (100 nM) or ... charybdotoxin (CTX; preferential high-conductance Ca2+-dependent K+-channel blocker), apamin (Apa; low-conductance Ca2+- ... the K+ channel blockers tetraethylammonium or charybdotoxin, or blockade of Ca2+ entry with lanthanum decreased [Ca2+]i by 54- ...

https://med.stanford.edu/profiles/david-cornfield

Animals were pretreated with glibenclamide (GLIB; 10 mg/kg, i.p.), apamin (APA; 0.04 mg/kg, i.p.), charybdotoxin (CHAR; 0.02, i ... Figure 7: Effect of glibenclamide, apamin, charybdotoxin, and tetraethylammonium chloride on MECN-induced antinociception in ... charybdotoxin (CHAR; an inhibitor of large conductance Ca2+-activated K+ channels, 0.02 mg/kg, i.p.), or tetraethylammonium ... charybdotoxin, and tetraethylammonium chloride). The results demonstrated that the orally administered MECN (100, 250, and 500 ...

https://www.hindawi.com/journals/prm/2018/9536406/

... only HuKIV has charybdotoxin sensitivity. Differences are observed between the pharmacological sensitivities of human channels ...

https://pubmed.ncbi.nlm.nih.gov/19912772/

Increases the binding activity of charybdotoxin (CTX) toxin to KCNMA1 peptide blocker by increasing the CTX association rate ... and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin.". Meera P., Wallner M., Toro L.. Proc. Natl. Acad. ... Increases the binding activity of charybdotoxin (CTX) toxin to KCNMA1 peptide blocker by increasing the CTX association rate ...

https://www.uniprot.org/uniprot/Q16558

Nuclear magnetic resonance structural studies of a potassium channel-charybdotoxin complex.. Yu L, Sun C, Song D, Shen J, Xu N ...

https://www.ncbi.nlm.nih.gov/pubmed?cmd=search&term=Gunasekera+A%5Bau%5D&dispmax=50

KCa channel function was assessed by extracellular application of; TEA (KCa inhibitor; 5mM), charybdotoxin (ChTx; BKCa and IKCa ...

http://www.physoc.org/proceedings/abstract/Proc%20Physiol%20Soc%2023PC359

Charybdotoxin. A potent and selective inhibitor of the large conductance Ca2+-activated K+ channels. 95751-30-7. sc-200979. 100 ...

https://www.scbt.com/browse/ik1-Inhibitors/_/N-1nd301k

5b). Thus, an inhibitory effect of XE991 on K+ channels is demonstrated, following EBIO and in the absence of charybdotoxin, ... Drugs used in the study, amiloride, charybdotoxin, clofilium, 1-ethyl-2-benzimidazolone (EBIO), and furosemide, were obtained ... charybdotoxin. Under these conditions, XE991 was able to reduce the response to EBIO by approximately 80%, as with forskolin ( ... XE991 was ineffective unless charybdotoxin was also present. Because EBIO also activates Ca2+-sensitive K+ channels, whereas ...

http://molpharm.aspetjournals.org/content/60/4/753

Charybdotoxin (ChTX), a K+ channel blocker, depolarizes human peripheral T lymphocytes and renders them insensitive to activation by mitogen. (pnas.org)
Charybdotoxin (ChTx) is a 37 amino acid peptide isolated from the venom of the scorpion Leiurus quinquestriatus hebraeus that blocks voltage-gated and large conductance Ca 2+ activated K + channels K Ca 1.1 in nanomolar concentrations (IC 50 ~ 3 nM). (smartox-biotech.com)
Charybdotoxin (ChTX), a protein present in the venom of the scorpion Leiurus quinquestriatus var. (smartox-biotech.com)
The fluoranthene-induced modulations of these anion transporters were counteracted by charybdotoxin (ChTx, a hIK-1 channel blocker). (aspetjournals.org)
Longitudinal phasic activity was increased under charybdotoxin (ChTx) treatment. (scirp.org)
Charybdotoxin (ChTX) blocks BK channel through physically occluding the K + -conduction pore. (monash.edu)

iv) prechallenged with inhibitors of various potassium channels (glibenclamide, apamin, charybdotoxin, and tetraethylammonium chloride). (hindawi.com)
1. The effect of intracerebroventricular (i.c.v.) administration of different potassium channel blockers (tetraethylammonium, apamin, charybdotoxin, gliquidone), potassium channel openers (pinacidil, minoxidil, cromakalim) and aODN to mKv1.1 on immobility time was evaluated in the mouse forced swimming test, an animal model of depression. (nih.gov)
5 microg per mouse i.c.v.), apamin (3 ng per mouse i.c.v.), charybdotoxin (1 microg per mouse i.c.v.) and gliquidone (6 microg per mouse i.c.v.) administered 20 min before the test produced anti-immobility comparable to that induced by the tricyclic antidepressants amitriptyline (15 mg kg(-1) s.c.) and imipramine (30 mg kg(-1) s.c.). 3. (nih.gov)
Effect of tetraethylammonium (TEA), apamin, charybdotoxin, gliquidone, amitriptyline (AMI) and imipramine (IMI) in the mouse forced swimming test. (nih.gov)
ATP-elicited delayed K + current was not inhibited by a 'cocktail' of K + channel blockers (4-AP, TEA, apamin, charybdotoxin, glibenclamide). (ingentaconnect.com)
The relaxation was inhibited by tetraethylammonium, ouabain, charybdotoxin plus apamin and under depolarization. (nii.ac.jp)
Responses to acetylcholine were assessed (in the presence of a nitric oxide synthase inhibitor) without or with the cyclooxygenase inhibitor diclofenac, the KCa inhibitors charybdotoxin plus apamin, or the BKCa inhibitor iberiotoxin. (ahajournals.org)
Diclofenac did not affect the MAS-induced impairment in the responses to acetylcholine, whereas charybdotoxin plus apamin virtually abolished the relaxation in both male wild-type and MAS mice. (ahajournals.org)
The BK channel was inhibited reversibly by external tetraethylammonium (TEA) ions, charybdotoxin, and quinine and was resistant to block by 4-aminopyridine and apamin. (edu.au)

2. The channel had a conductance of 210 pS in a 150 mM:150 mM K+ gradient, was highly selective for K+ over Na+, and was sensitive to block by external charybdotoxin or tetraethylammonium (TEA) and by internal Ba2+. (nih.gov)
ESB-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA), a nonselective K + channel blocker, and charybdotoxin, a selective Ca 2+ -dependent K + channel inhibitor. (hindawi.com)
The effect of tamoxifen was always obtained in the first minute, peaked at 5.9 ± 2.2 min ( n = 23), and was abolished by the perfusion of tetraethylammonium (0.5 mM), charybdotoxin (50 nM), or iberiotoxin (100 nM). (aspetjournals.org)
Relaxations to both carbachol and sodium nitroprusside were attenuated in the presence of raised extracellular potassium and the potassium channel blockers charybdotoxin, iberiotoxin and tetraethylammonium. (portlandpress.com)
Other channel blockers include: charybdotoxin, iberiotoxin and tetraethylammonium. (guidetopharmacology.org)
The intracerebroventricular administration of tetraethylammonium (TEA, a nonspecific blocker of K(+) channels), glibenclamide (an ATP-sensitive K(+) channel blocker), charybdotoxin (a large- and intermediate-conductance calcium-activated K(+) channel blocker) or apamin (a small-conductance calcium-activated K(+) channel blocker) combined with a subeffective dose of hesperidin (0.01 mg/kg, intraperitoneally [i.p.]) was able to produce a synergistic antidepressant-like effect in the mice TST. (sigmaaldrich.com)

Purification, sequence, and model structure of charybdotoxin, a potent selective inhibitor of calcium-activated potassium channels. (hellobio.com)
Charybdotoxin, an inhibitor of Ca ++ -activated K + channels, reduced vasodilator responses to Ach without affecting those to cromakalim or nitroprusside. (elsevier.com)
Different EET regioisomers hyperpolarized platelets down to −69±2 mV, which was prevented by the non-specific potassium channel inhibitor charybdotoxin and by use of a blocker of calcium-activated potassium channels of large conductance (BK Ca channels), iberiotoxin. (ahajournals.org)
Charybdotoxin (CTX) is an inhibitor of large conductance K + Ca2+ , intermediate conductance K + Ca2+ (IK Ca2+ ), and voltage-dependent potassium channels. (jci.org)
For example, charybdotoxin blocks voltage-gated Kv channels with exquisite potency [Ki (inhibitor constant) in the subnanomolar range] ( 4 ), causing uncontrollable hyperexcitability of the nervous system ( 5 , 6 ). (sciencemag.org)

Mammalian BK channels are characterized by their high sensitivity to blockade by iberiotoxin (IbTx) and charybdotoxin. (epfl.ch)

19 20 21 22 23 These reports differ in the type of K + channel affected by NO: two reports indicate inhibition by glibenclamide, 19 22 whereas two other reports indicate inhibition by charybdotoxin. (ahajournals.org)

Charybdotoxin and margatoxin acting on the human voltage-gated potassium channel hKv1.3 and its H399N mutant: an experimental and computational comparison. (hellobio.com)
Charybdotoxin (CTX) * and margatoxin (MgTX), which block the predominant voltage-dependent potassium (Kv) channel (Kv1.3) of peripheral lymphocytes, depolarize the plasma membrane ( 3 - 5 ), and thereby inhibit TCR-mediated calcium influx ( 6 - 8 ), IL-2 production ( 9 ), and proliferation ( 9 , 10 ). (rupress.org)

Using human intermediate-conductance calcium-activated potassium (hIKCa1) channels as a model we aimed to characterize structural differences between maurotoxin (MTX) and charybdotoxin (CTX) and to gain new insights into the molecular determinants that define the interaction of these pore-blocking peptides with hIKCa1 channel. (ovid.com)
These results suggest that in the rat kidney, Ach, like bradykinin, utilizes a charybdotoxin-sensitive Ca ++ -activated K + channel of intermediate conductance to elicit vasodilation and that this effect may be dependent on cytochrome P450 activity. (elsevier.com)

Biological activity on dog epithelial Ca(2+)-activated K+ channels and on rat brain synaptosomal voltage-dependent K+ channels show that synthetic charybdotoxin was as potent as the natural toxin on both channels. (strath.ac.uk)
Increases the binding activity of charybdotoxin (CTX) toxin to KCNMA1 peptide blocker by increasing the CTX association rate and decreasing the dissociation rate. (uniprot.org)
Makes KCNMA1 channel resistant to 100 nM charybdotoxin (CTX) toxin concentrations. (genecards.org)

The TTX- and atropine-sensitive twitches of guinea pig ileum are also induced by nanomolar concentrations of α-dendrotoxin, a selective blocker of Shaker K v 1.1 and 1.2 subtypes, or stichodactylatoxin, a peptide isolated from sea anemone that displays high affinity for K v 1.1 and 1.3, but not by charybdotoxin, which blocks K v 1.2 and 1.3 but not 1.1. (aspetjournals.org)

Sands SB, Lewis RS and Cahalan MD: Charybdotoxin blocks voltage-gated K+ channels in T lymphocytes. (springer.com)

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)
[4] Charybdotoxin, a 37 amino acid, 4 kDa neurotoxin with the molecular formula C 176 H 277 N 57 O 55 S 7 , is one of the peptide toxins that can be extracted from the venom of the scorpion. (wikipedia.org)
The charybdotoxin receptor of a Shaker K+ channel: peptide and channel residues mediating molecular recognition. (smartox-biotech.com)
Charybdotoxin (CTX) is a peptide of known structure that inhibits Shaker K+ channels by a pore-blocking mechanism. (smartox-biotech.com)

Inhibition by charybdotoxin. (rupress.org)
The calcium-mediated inhibition of rehydration was reversed by charybdotoxin, implying that rehydration was delayed in some cells by the Ca(++)-activated K(+) channel. (unboundmedicine.com)

Mechanism of charybdotoxin block of the high-conductance, Ca2+-activated K+ channel. (rupress.org)
Part of this conductance (35 +/- 5%) could be blocked by charybdotoxin and stimulated by ionomycin (10(-5) mol/1). (arvojournals.org)
Meera P, Wallner M, Toro L A neuronal beta subunit (KCNMB4) makes the large conductance, voltage- and Ca2+-activated K+ channel resistant to charybdotoxin and iberiotoxin Proc. (ucla.edu)

Charybdotoxin binding in the I(Ks) pore demonstrates two MinK subunits in each channel complex. (escholarship.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)
The three-dimensional structure of Pi3 is similar to other potassium channel blocking toxins like charybdotoxin, because it has three disulphide bridges that stabilize two strands of beta sheet structures and a short alpha helix. (wikipedia.org)
The amino terminal region of Pi3 lacks three residues when compared to other toxins of the same family e.g. charybdotoxin. (wikipedia.org)
The Pandinotoxins, PiTX-K alpha and PiTX-K beta, are members of the Charybdotoxin family of scorpion toxins that can be used to characterize K+ channels. (rcsb.org)

Moreover, basolateral treatment with either charybdotoxin or clotrimazole significantly inhibited the initial UTP-dependent increase in I sc and eliminated the sustained current response. (umn.edu)

Charybdotoxin (CTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus (deathstalker) that blocks calcium-activated potassium channels. (wikipedia.org)
Charybdotoxin occludes the pore of calcium-activated voltage-gated shaker K+ channels by binding to one of four independent, overlapping binding sites. (wikipedia.org)
K DR currents were not sensitive to charybdotoxin, which blocks homotetrameric Kv1.2 channels. (ahajournals.org)
We examined the effects of Phentolamine (200 µM) and Charybdotoxin (50 nM), which are both inhibitors of the Ca + sensitive Cl - channels of the 4TM, 2P K + channel. (sicb.org)
BKB4 channels were not blocked by 100 nM charybdotoxin or iberiotoxin, and were activated by 17-beta-estradiol. (epfl.ch)

Charybdotoxin prevent the movement of K+ movement by obstructing the pore of the calcium activated potassium channel and this leads to the prolonged duration of an action potential. (ukessays.com)

However, when 1-ethyl-2-benzimidazolinone (EBIO) was used to stimulate chloride secretion, XE991 was ineffective unless charybdotoxin was also present. (aspetjournals.org)
The channel could be blocked by external charybdotoxin (10(-8) mol/1), external TEA+ tetraethyl ammonium chloride (1 mmol/l) and by internal Ba2+ (10 mmol/l), whereas external Ba2+ and internal TEA+ (10 mmol/l) had no effect. (arvojournals.org)

Mechanism of charybdotoxin block of a voltage-gated K+ channel. (smartox-biotech.com)

Charybdotoxin block of a Shaker K+ channel was studied in Xenopus oocyte macropatches. (smartox-biotech.com)
Detection of unbinding transitional states in the charybdotoxin first-order dissociation from a Kv-channel reveals that the bound neurotoxin wobbles, suggesting diverse intermediates and dissociation pathways in this protein-protein interaction. (elifesciences.org)
channel also produced a concentration-dependent relaxation, which was inhibited by charybdotoxin, ouabai … More n and depolarization, but independent of NO and prostacyclin. (nii.ac.jp)

5. Unitary and spontaneous transient outward currents were inhibited by extracellularly applied TEA (0.5 mM), TBA (0.5-5 mM) and charybdotoxin (100 nM). (edu.au)

Charybdotoxin and two N-terminal truncated peptides, corresponding to the 2-37 and 7-37 sequences, were obtained by stepwise solid-phase synthesis using N alpha-t-butyloxycarbonyl and benzyltype side-chain protection. (strath.ac.uk)

Charybdotoxin is a neurotoxin which is a substance of the venom of the Leiurus quinquestriatus hebraeus scorpion. (ukessays.com)

Charge neutralization of charybdotoxin Lys27, however, renders off rate voltage insensitive. (smartox-biotech.com)

only HuKIV has charybdotoxin sensitivity. (nih.gov)

We conclude that the N-terminal region of charybdotoxin plays a functional role in tuning the toxin's biological activity but is not essential for the folding and stability of the structure. (strath.ac.uk)

NMR data show that synthetic charybdotoxin is indistinguishable from the natural protein. (strath.ac.uk)

Charybdotoxin" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (childrensmercy.org)

This effect was blocked by TEA and charybdotoxin. (ahajournals.org)
The hyperpolarizing effect of SNAP was decreased by ODQ, glybenclamide and (or) charybdotoxin. (iospress.com)