Batrachotoxin is the 20-alpha-bromobenzoate of batrachotoxin A; they are toxins from the venom of a small Colombian frog, Phyllobates aurotaenia, cause release of acetylcholine, destruction of synaptic vesicles and depolarization of nerve and muscle fibers.
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.
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)
A compound that contains a reduced purine ring system but is not biosynthetically related to the purine alkaloids. It is a poison found in certain edible mollusks at certain times; elaborated by GONYAULAX and consumed by mollusks, fishes, etc. without ill effects. It is neurotoxic and causes RESPIRATORY PARALYSIS and other effects in MAMMALS, known as paralytic SHELLFISH poisoning.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
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).
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 benzoate-cevane found in VERATRUM and Schoenocaulon. It activates SODIUM CHANNELS to stay open longer than normal.
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.
An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.
The nonstriated involuntary muscle tissue of blood vessels.
It is a form of protection provided by law. In the United States this protection is granted to authors of original works of authorship, including literary, dramatic, musical, artistic, and certain other intellectual works. This protection is available to both published and unpublished works. (from Circular of the United States Copyright Office, 6/30/2008)
Protective measures against unauthorized access to or interference with computer operating systems, telecommunications, or data structures, especially the modification, deletion, destruction, or release of data in computers. It includes methods of forestalling interference by computer viruses or so-called computer hackers aiming to compromise stored data.
The privacy of information and its protection against unauthorized disclosure.
The state of being free from intrusion or disturbance in one's private life or affairs. (Random House Unabridged Dictionary, 2d ed, 1993)
Behaviors associated with the ingesting of alcoholic beverages, including social drinking.
Alkyl compounds containing a hydroxyl group. They are classified according to relation of the carbon atom: primary alcohols, R-CH2OH; secondary alcohols, R2-CHOH; tertiary alcohols, R3-COH. (From Grant & Hackh's Chemical Dictionary, 5th ed)
The legal authority or formal permission from authorities to carry on certain activities which by law or regulation require such permission. It may be applied to licensure of institutions as well as individuals.
Proposed spasmolytic with possible local anesthetic action used in gastrointestinal disorders.
Compounds with activity like OPIATE ALKALOIDS, acting at OPIOID RECEPTORS. Properties include induction of ANALGESIA or NARCOSIS.
Compounds capable of relieving pain without the loss of CONSCIOUSNESS.
A class of opioid receptors recognized by its pharmacological profile. Mu opioid receptors bind, in decreasing order of affinity, endorphins, dynorphins, met-enkephalin, and leu-enkephalin. They have also been shown to be molecular receptors for morphine.
A potent noncompetitive antagonist of the NMDA receptor (RECEPTORS, N-METHYL-D-ASPARTATE) used mainly as a research tool. The drug has been considered for the wide variety of neurodegenerative conditions or disorders in which NMDA receptors may play an important role. Its use has been primarily limited to animal and tissue experiments because of its psychotropic effects.
Exclusive legal rights or privileges applied to inventions, plants, etc.
Cell membrane proteins that bind opioids and trigger intracellular changes which influence the behavior of cells. The endogenous ligands for opioid receptors in mammals include three families of peptides, the enkephalins, endorphins, and dynorphins. The receptor classes include mu, delta, and kappa receptors. Sigma receptors bind several psychoactive substances, including certain opioids, but their endogenous ligands are not known.
The science concerned with celestial bodies and the observation and interpretation of the radiation received in the vicinity of the earth from the component parts of the universe (McGraw Hill Dictionary of Scientific and Technical Terms, 5th ed)
The sixth planet in order from the sun. It is one of the five outer planets of the solar system. Its twelve natural satellites include Phoebe and Titan.
Celestial bodies orbiting around the sun or other stars.
The natural satellite of the planet Earth. It includes the lunar cycles or phases, the lunar month, lunar landscapes, geography, and soil.
The fifth planet in order from the sun. It is one of the five outer planets of the solar system. Its sixteen natural satellites include Callisto, Europa, Ganymede, and Io.
The fourth planet in order from the sun. Its two natural satellites are Deimos and Phobos. It is one of the four inner or terrestrial planets of the solar system.
The second planet in order from the sun. It has no known natural satellites. It is one of the four inner or terrestrial planets of the solar system.
Neurologic disorders caused by exposure to toxic substances through ingestion, injection, cutaneous application, or other method. This includes conditions caused by biologic, chemical, and pharmaceutical agents.
Sounds used in animal communication.
Modulation of human voice to produce sounds augmented by musical tonality and rhythm.
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.
Common name for small PASSERIFORMES in the family Fringillidae. They have a short stout bill (BEAK) adapted for crushing SEEDS. Some species of Old World finches are called CANARIES.
PASSERIFORMES of the suborder, Oscines, in which the flexor tendons of the toes are separate, and the lower syrinx has 4 to 9 pairs of tensor muscles inserted at both ends of the tracheal half rings. They include many commonly recognized birds such as CROWS; FINCHES; robins; SPARROWS; and SWALLOWS.
Warm-blooded VERTEBRATES possessing FEATHERS and belonging to the class Aves.
Common name for two distinct groups of BIRDS in the order GALLIFORMES: the New World or American quails of the family Odontophoridae and the Old World quails in the genus COTURNIX, family Phasianidae.
Large woodland game BIRDS in the subfamily Meleagridinae, family Phasianidae, order GALLIFORMES. Formerly they were considered a distinct family, Melegrididae.
Instinctual behavior pattern in which food is obtained by killing and consuming other species.
The forcible expulsion of the contents of the STOMACH through the MOUTH.
Substances which, when ingested, inhaled, or absorbed, or when applied to, injected into, or developed within the body in relatively small amounts may, by their chemical action, cause damage to structure or disturbance of function. (From Dorland, 27th ed)

BIIR 561 CL: a novel combined antagonist of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and voltage-dependent sodium channels with anticonvulsive and neuroprotective properties. (1/132)

Antagonists of glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype, as well as of voltage-gated sodium channels, exhibit anticonvulsive and neuroprotective properties in vivo. One can postulate that a compound that combines both principles might be useful for the treatment of disorders of the central nervous system, like focal or global ischemia. Here, we present data on the effects of dimethyl-(2-[2-(3-phenyl-[1,2, 4]oxadiazol-5-yl)-phenoxy]ethyl)-amine hydrochloride (BIIR 561 CL) on neuronal AMPA receptors and voltage-dependent sodium channels. BIIR 561 CL inhibited AMPA receptor-mediated membrane currents in cultured cortical neurons with an IC50 value of 8.5 microM. The inhibition was noncompetitive. In a cortical wedge preparation, BIIR 561 CL reduced AMPA-induced depolarizations with an IC50 value of 10.8 microM. In addition to the effects on the glutamatergic system, BIIR 561 CL inhibited binding of radiolabeled batrachotoxin to rat brain synaptosomal membranes with a Ki value of 1.2 microM. The compound reduced sodium currents in voltage-clamped cortical neurons with an IC50 value of 5.2 microM and inhibited the veratridine-induced release of glutamate from rat brain slices with an IC50 value of 2.3 microM. Thus, BIIR 561 CL inhibited AMPA receptors and voltage-gated sodium channels in a variety of preparations. BIIR 561 CL suppressed tonic seizures in a maximum electroshock model in mice with an ED50 value of 2.8 mg/kg after s.c. administration. In a model of focal ischemia in mice, i.p. administration of 6 or 60 mg/kg BIIR 561 CL reduced the area of the infarcted cortical surface. These data show that BIIR 561 CL is a combined antagonist of AMPA receptors and voltage-gated sodium channels with promising anticonvulsive and neuroprotective properties.  (+info)

Pharmacological properties of trimebutine and N-monodesmethyltrimebutine. (2/132)

Trimebutine [2-dimethylamino-2-phenylbutyl-3,4,5-trimethoxybenzoate hydrogen maleate (TMB)] has been demonstrated to be active for relieving abdominal pain in humans. To better understand its mechanism of action, we have tested TMB; nor-TMB, its main metabolite in humans; and their respective stereoisomers for their affinity toward sodium channels labeled by [3H]batrachotoxin, their effect on sodium, potassium, and calcium currents in rat dorsal root ganglia neurons, and their effect on veratridine-induced glutamate release from rat spinal cord slices. TMB has also been tested in an animal model of local anesthesia. TMB (Ki = 2.66 +/- 0.15 microM) and nor-TMB (Ki = 0.73 +/- 0.02 microM) displaced [3H]batrachotoxin from its binding site with affinities similar to that of bupivacaine (Ki = 7.1 +/- 0.9 microM). nor-TMB was found to block veratridine-induced glutamate release with an IC50 value of 8.5 microM, which is very similar to that of bupivacaine (IC50 = 8.2 microM); the effect of TMB was limited to 50% inhibition at 100 microM. TMB and nor-TMB blocked sodium currents in sensory neurons from rat dorsal root ganglia (IC50 = 0.83 +/- 0.09 and 1.23 +/- 0.19 microM, respectively), whereas no effect was observed on calcium currents at the same concentrations. A limited effect was observed on potassium currents (IC50 = 23 +/- 6 at 10 microM) for TMB. In vivo, when tested in the rabbit corneal reflex, TMB displayed a local anesthetic activity 17-fold more potent than that of lidocaine.  (+info)

Batrachotoxin-resistant Na+ channels derived from point mutations in transmembrane segment D4-S6. (3/132)

Local anesthetics (LAs) block voltage-gated Na+ channels in excitable cells, whereas batrachotoxin (BTX) keeps these channels open persistently. Previous work delimited the LA receptor within the D4-S6 segment of the Na+ channel alpha-subunit, whereas the putative BTX receptor was found within the D1-S6. We mutated residues at D4-S6 critical for LA binding to determine whether such mutations modulate the BTX phenotype in rat skeletal muscle Na+ channels (mu1/rSkm1). We show that mu1-F1579K and mu1-N1584K channels become completely resistant to 5 microM BTX. In contrast, mu1-Y1586K channels remain BTX-sensitive; their fast and slow inactivation is eliminated by BTX after repetitive depolarization. Furthermore, we demonstrate that cocaine elicits a profound time-dependent block after channel activation, consistent with preferential LA binding to BTX-modified open channels. We propose that channel opening promotes better exposure of receptor sites for binding with BTX and LAs, possibly by widening the bordering area around D1-S6, D4-S6, and the pore region. The BTX receptor is probably located at the interface of D1-S6 and D4-S6 segments adjacent to the LA receptor. These two S6 segments may appose too closely to bind BTX and LAs simultaneously when the channel is in its resting closed state.  (+info)

Point mutations at N434 in D1-S6 of mu1 Na(+) channels modulate binding affinity and stereoselectivity of local anesthetic enantiomers. (4/132)

Voltage-gated Na(+) channels are the primary targets of local anesthetics (LAs). Amino acid residues in domain 4, transmembrane segment 6 (D4-S6) form part of the LA binding site. LAs inhibit binding of the neurotoxin batrachotoxin (BTX). Parts of the BTX binding site are located in D1-S6 and D4-S6. The affinity of BTX-resistant Na(+) channels mutated in D1-S6 (mu1-N434K, mu1-N437K) toward several LAs is significantly decreased. We have studied how residue mu1-N434 influences LA binding. By using site-directed mutagenesis, we created mutations at mu1-N434 that vary the hydrophobicity, aromaticity, polarity, and charge and investigated their influence on state-dependent binding and stereoselectivity of bupivacaine. Wild-type and mutant channels were transiently expressed in human embryonic kidney 293t cells and investigated under whole-cell voltage-clamp. For resting channels, bupivacaine enantiomers showed a higher potency in all mutant channels compared with wild-type channels. These changes were not well correlated with the physical properties of the substituted residues. Stereoselectivity was small and almost unchanged. In inactivated channels, the potency of bupivacaine was increased in mutations containing a quadrupole of an aromatic group (mu1-N434F, mu1-N434W, mu1-N434Y), a polar group (mu1-N434C), or a negative charge (mu1-N434D) and was decreased in a mutation containing a positive charge (mu1-N434K). In mutation mu1-N434R, containing the positively charged arginine, the potency of S(-)-bupivacaine was selectively decreased, resulting in a stereoselectivity (stereopotency ratio) of 3. Similar results were observed with cocaine but not with RAC 109 enantiomers. We propose that in inactivated channels, residue mu1-N434 interacts directly with the positively charged moiety of LAs and that D1-S6 and D4-S6 form a domain-interface site for binding of BTX and LAs in close proximity.  (+info)

Cooperative activation of action potential Na+ ionophore by neurotoxins. (5/132)

Four neurotoxins that activate the action potential Na+ ionophore of electrically excitable neuroblastoma cells interact with two distinct classes of sites, one specific for the alkaloids veratridine, batrachotoxin, and aconitine, and the second specific for scorpion toxin. Positive heterotropic cooperativity is observed between toxins bound at these two classes of sites. Tetrodotoxin is a noncompetitive inhibitor of activation by each of these toxins (KI = 4-8 nM). These results suggest the existence of three functionally separable components of the action potential Na+ ionophore: two regulatroy components, which bind activating neurotoxins and interact allosterically in controlling the activity of a third ion-transport component, which binds tetrodotoxin.  (+info)

Rapid and slow voltage-dependent conformational changes in segment IVS6 of voltage-gated Na(+) channels. (6/132)

Mutations in segment IVS6 of voltage-gated Na(+) channels affect fast-inactivation, slow-inactivation, local anesthetic action, and batrachotoxin (BTX) action. To detect conformational changes associated with these processes, we substituted a cysteine for a valine at position 1583 in the rat adult skeletal muscle sodium channel alpha-subunit, and examined the accessibility of the substituted cysteine to modification by 2-aminoethyl methanethiosulfonate (MTS-EA) in excised macropatches. MTS-EA causes an irreversible reduction in the peak current when applied both internally and externally, with a reaction rate that is strongly voltage-dependent. The rate increased when exposures to MTS-EA occurred during brief conditioning pulses to progressively more depolarized voltages, but decreased when exposures occurred at the end of prolonged depolarizations, revealing two conformational changes near site 1583, one coupled to fast inactivation, and one tightly associated with slow inactivation. Tetraethylammonium, a pore blocker, did not affect the reaction rate from either direction, while BTX, a lipophilic activator of sodium channels, completely prevented the modification reaction from occurring from either direction. We conclude that there are two inactivation-associated conformational changes in the vicinity of site 1583, that the reactive site most likely faces away from the pore, and that site 1583 comprises part of the BTX receptor.  (+info)

Betaxolol, a beta(1)-adrenoceptor antagonist, reduces Na(+) influx into cortical synaptosomes by direct interaction with Na(+) channels: comparison with other beta-adrenoceptor antagonists. (7/132)

Betaxolol, a beta(1)-adrenoceptor antagonist used for the treatment of glaucoma, is known to be neuroprotective in paradigms of ischaemia/excitotoxicity. In this study, we examined whether betaxolol and other beta-adrenoceptor antagonists interact directly with neurotoxin binding to sites 1 and 2 of the voltage-sensitive sodium channel (Na(+) channel) in rat cerebrocortical synaptosomes. Betaxolol inhibited specific [(3)H]-batrachotoxinin-A 20-alpha-benzoate ([(3)H]-BTX-B) binding to neurotoxin site 2 in a concentration-dependent manner with an IC(50) value of 9.8 microM. Comparison of all the beta-adrenoceptor antagonists tested revealed a potency order of propranolol>betaxolol approximately levobetaxolol>levobunolol approximately carteolol>/=timolol>atenolol. None of the drugs caused a significant inhibition of [(3)H]-saxitoxin binding to neurotoxin receptor site 1, even at concentrations as high as 250 microM. Saturation experiments showed that betaxolol increased the K(D) of [(3)H]-BTX-B binding but had no effect on the B(max). The association kinetics of [(3)H]-BTX-B were unaffected by betaxolol, but the drug significantly accelerated the dissociation rate of the radioligand. These findings argue for a competitive, indirect, allosteric mode of inhibition of [(3)H]-BTX-B binding by betaxolol. Betaxolol inhibited veratridine-stimulated Na(+) influx in rat cortical synaptosomes with an IC(50) value of 28. 3 microM. Carteolol, levobunolol, timolol and atenolol were significantly less effective than betaxolol at reducing veratridine-evoked Na(+) influx. The ability of betaxolol to interact with neurotoxin site 2 of the Na(+) channel and inhibit Na(+) influx may have a role in its neuroprotective action in paradigms of excitotoxicity/ischaemia and in its therapeutic effect in glaucoma.  (+info)

Residues in Na(+) channel D3-S6 segment modulate both batrachotoxin and local anesthetic affinities. (8/132)

Batrachotoxin (BTX) alters the gating of voltage-gated Na(+) channels and causes these channels to open persistently, whereas local anesthetics (LAs) block Na(+) conductance. The BTX and LA receptors have been mapped to several common residues in D1-S6 and D4-S6 segments of the Na(+) channel alpha-subunit. We substituted individual residues with lysine in homologous segment D3-S6 of the rat muscle mu1 Na(+) channel from F1274 to N1281 to determine whether additional residues are involved in BTX and LA binding. Two mutant channels, mu1-S1276K and mu1-L1280K, when expressed in mammalian cells, become completely resistant to 5 microM BTX during repetitive pulses. The activation and/or fast inactivation gating of these mutants is substantially different from that of wild type. These mutants also display approximately 10-20-fold reduction in bupivacaine affinity toward their inactivated state but show only approximately twofold affinity changes toward their resting state. These results demonstrate that residues mu1-S1276 and mu1-L1280 in D3-S6 are critical for both BTX and LA binding interactions. We propose that LAs interact readily with these residues from D3-S6 along with those from D1-S6 and D4-S6 in close proximity when the Na(+) channel is in its inactivated state. Implications of this state-dependent binding model for the S6 alignment are discussed.  (+info)

0069] Blockade of voltage-sensitive sodium channels was studied by investigating [3H] batrachotoxinin A 20-R-benzoate ([3H]BTX) displacement binding to whole brain membranes. Animals were decapitated and their brains quickly removed. Membrane preparation and binding assays were performed essentially as previously described (Shimidzu et al., 1997). Brains (without cerebellum) were homogenised in 10 vol 0.32 M sucrose, 1 mM EDTA, 1 mg/ml bovine serum albumin (BSA), 5 mM HEPES/TRIS pH 7.4 with a Teflon homogeniser (8 strokes at 400 r.p.m). After a 10 min centrifugation at 1,000 g the supernatants were centrifuged for 20 min at 39,000 g and pellets were homogenised with 20 vol or 40 vol Na+-free buffer, respectively for [3H]-batrachotoxinin A 20-alpha-benzoate ([3H]-BTX) binding assays. Na+-free buffer had the following composition (in mM): 130 choline chloride, 0.8 MgSO4, 5.4 KCl, 5.5 D-glucose, 50 HEPES/TRIS, pH 7.4. The homogenate was centrifuged for 20 min at 39,000 g and the resultant pellets ...
Elin E.A.; Grishin E.V.; Leonov V.N.; Prosolova T.K.; Soldatov N.M.; Torgov I.V.; Myasoedov N.F.; Shevchenko V.P., 1983: Synthesis and biological activity of 7 8 di hydro batrachotoxinin derivatives interacting with fast sodium channels
Direct evidence for ATX interaction with VGSC was derived from the demonstration of stimulation of [3H]batrachotoxin binding and sodium influx by ATX in cultured neurons [11,12 ...
The alkaloid ervatamine blocks the voltage-sensitive Na+ conductance. EC50 for different cell lines and for synaptosomes range between 1-3 and 5-12 µM. The toxic compound also alters the K+ conductance, although less efficiently than the Na+ conductance. Epiervatamine, a structural analogue of ervatamine, is 4-8 times more potent than ervatamine. Dose-response curves for ervatamine and epiervatamine show that the compounds bind to a single class of binding sites. Competition experiments with a radiolabeled tetrodotoxin (TTX) derivative indicate that these binding sites are distinct from the TTX receptor site. Ervatamine and epiervatamine seem to inhibit the Na+ current (or Na+ flux) by acting on the channel-gating mechanism. 22Na+ uptake measurements with neuroblastoma cells show that epiervatamine is a competitive inhibitor of the action of batrachotoxin, a well known specific activator of the Na+ channel. The dissociation constant of epiervatamine from its receptor site is 1.7 µM, very ...
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In 1990 scientists preparing the skins of the hooded pitohui for museum collections experienced numbness and burning when handling them. It was reported in 1992 that this species and some other pitohuis contained a neurotoxin called homobatrachotoxin, a derivative of batrachotoxin, in their tissues. This made them the first documented poisonous birds,[13] other than some reports of coturnism caused by consuming quail (although toxicity in quails is unusual), and the first bird discovered with toxins in the skin.[14] The same toxin had previously only been found in Colombian poison dart frogs from the genus Phyllobates (family Dendrobatidae). The batrachotoxin family of compounds are the most toxic compounds by weight in nature,[15] being 250 times more toxic than strychnine.[16] Later research found that the hooded pitohui had other batrachotoxins in its skin, including batrachotoxinin-A cis-crotonate, batrachotoxinin-A and batrachotoxinin-A 3′-hydroxypentanoate.[17]. Bioassays of their tissue ...
Batrachotoxin (BTX), from South American frogs of the genusPhyllobates, irreversibly activates voltage-gated sodium channels. Previous work demonstrated that a phenylalanine residue approximately halfway through pore-lining transmembrane segment IVS6 is a critical determinant of channel sensitivity to BTX. In this study, we introduced a series of mutations at this site in the Nav1.3 sodium channel, expressed wild-type and mutant channels inXenopus laevis oocytes, and examined their sensitivity to BTX using voltage clamp recording. We found that substitution of either alanine or isoleucine strongly reduced channel sensitivity to toxin, whereas cysteine, tyrosine, or tryptophan decreased toxin action only modestly. These data suggest an electrostatic ligand-receptor interaction at this site, possibly involving a charged tertiary amine on BTX. We then used a mutant channel (mutant F1710C) with intermediate toxin sensitivity to examine the properties of the toxin-receptor reaction in more detail. In ...
BTX this week introduced MicroPoration, a new method for non viral transfections. With this new method, transfection takes place in the actual pipette tip.
In general, Botox is the brand name for a botulin toxin type A, of which there are subtypes. The type B variety (BTX-B) is known as Neurobloc in the E.U. or Myobloc in…. ...
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TY - JOUR. T1 - Voltage-dependent sodium channel function is regulated through membrane mechanics. AU - Shcherbatko, Anatoly. AU - Ono, Fumihito. AU - Mandel, Gail. AU - Brehm, Paul. PY - 1999/10. Y1 - 1999/10. N2 - Cut-open recordings from Xenopus oocytes expressing either nerve (PN1) or skeletal muscle (SkM1) Na+ channel α subunits revealed slow inactivation onset and recovery kinetics of inward current. In contrast, recordings using the macropatch configuration resulted in an immediate negative shift in the voltage-dependence of inactivation and activation, as well as time-dependent shifts in kinetics when compared to cut-open recordings. Specifically, a slow transition from predominantly slow onset and recovery to exclusively fast onset and fast recovery from inactivation occurred. The shift to fast inactivation was accelerated by patch excision and by agents that disrupted microtubule formation. Application of positive pressure to cell-attached macropatch electrodes prevented the shift in ...
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TY - JOUR. T1 - Vascular smooth muscle contraction induced by Na+ channel activators, veratridine and batrachotoxin. AU - Shinjo(H), Masayoshi. AU - Toshio, Nakaki. AU - Yukari, Otsuka. AU - Nobuyuki, Sasakawa. AU - Ryuichi, Kato. PY - 1991/11/26. Y1 - 1991/11/26. N2 - The effects of the sodium channel activators veratridine and batrachotoxin on isolated rat aorta were investigated. Veratridine caused gradual contraction, independent of the presence of endolhelium, with an EC50 of 35 μM. Batrachotoxin (1 μM) also induced contraction. Both effects were completely inhibited by the sodium channel blocker tetrodotoxin (1 μM). The veratridine (60 μM)-induced contraction was inhibited by nifedipine (0.1 μM). In the absence of extracellular Ca2+, veratridine (60 μm) did not cause contraction. Sodium nitroprusside (80 nM), acetylcholine (10 μM) and isoproterenol (1 μM) caused relaxation of rings precontracted with veratridine (60 μM). An inhibitor of endothelium-derived relaxing factor (EDRF) ...
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Extra info: During depolarization, sodium ions enter the cell via the voltage-dependent sodium channels. This results in a switch of the membrane potential. In order to return to a potential below the threshold, the ATP-dependent Na+/K+ pump actively pumps the sodium ions out of the cell (and potassium ions back in.). ...
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Background: Mutations in voltage gated brain sodium channel Nav1.1 have been linked to many disorders, including Generalized Epilepsy with Febrile Seizures Plus (GEFS+) and Severe Myoclonic Epilepsy of Infancy (SMEI). Recent studies have identified TTX- sensitive Nav1.1 brain sodium channels in the SA node and ventricular T-tubules of the heart, though their role in cardiac function is still controversial. We tested the functional significance of Nav1.1 sodium channels in the heart by creating a novel knock-in of human epilepsy GEFS+ mutation SCN1A-R1648H at the Scn1a locus of a C57BL/6J X 129 mouse.. Method: In vivo 2-D echocardiography was performed on 2 week old (juvenile) and 8 week old (adult) wild-type and heterozygote (Scn1aRH/+) mice after extracardiac neuronal block through intraperitoneal injections of atropine and propranolol (2.5mg/kg each). Calcium and contractility studies on adult ventricular cardiomyocytes isolated from the wild type and Scn1aRH/+ mice paced at 0.5Hz were ...
Previously cloned voltage-dependent sodium channels exhibit a high degree of homology to one another and appear to comprise a single multigene family. We have now isolated and characterized cDNAs from both human adult heart and fetal skeletal muscle that encode a sodium channel alpha subunit that exhibits only moderate primary structure identity with other sodium channels and is prominently expressed in both heart and uterus. The approximately 7.2-kilobase cDNA sequence, designated hNav2.1, predicts a 1682-amino acid protein that bears 52%, 49%, and 46% overall identity with sodium channels cloned from rat brain, skeletal muscle, and heart, respectively. Positively charged S4 segments are present in hNav2.1, but there are fewer basic residues in repeat domains 1, 3, and 4 than in other cloned sodium channels. The cloning of hNav2.1 provides evidence for greater evolutionary divergence among voltage-dependent sodium channels and suggests that other sodium channel gene subfamilies may exist. The ...
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Definition of benzocaine in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is benzocaine? Meaning of benzocaine as a legal term. What does benzocaine mean in law?
Neurons process and transmit information in the form of electrical signals. Their electrical excitability is due to the presence of voltage-sensitive ion channels in the neuronal plasma membrane. In recent years, the voltage-sensitive sodium channel of mammalian brain has become the first of these important neuronal components to be studied at the molecular level. This article describes the distribution of sodium channels among the functional compartments of the neuron and reviews work leading to the identification, purification, and characterization of this membrane glycoprotein.. ...
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Sodium channels expressed in cardiac muscle cells are resistant to nanomolar concentrations of TTX, and require micromolar concentrations for inhibition. On the other hand, these channels are more sensitive to inhibition by lidocaine than are CNS channels.. The receptor sites for these toxins are formed by amino acid residues in the pore loops and immediately on the extracellular side of the pore loops at the outer end of the pore. Neurotoxin receptor site 2 binds a family of lipid-soluble toxins, including batrachotoxin, veratridine, aconitine, and grayanotoxin, which enhance activation of sodium channels. Photoaffinity labeling and mutagenesis studies implicate transmembrane segments IS6 and IVS6 in the receptor site for batrachotoxin [815]. Neurotoxin receptor site 3 binds the alpha-scorpion toxins and sea anemone toxins, which slow the coupling of sodium channel activation to inactivation. These peptide toxins bind to a complex receptor site that includes the S3-S4 loop at the outer end of ...
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Gellens ME, George AL, Chen LQ, Chahine M, Horn R, Barchi RL, Kallen RG. Primary structure and functional expression of the human cardiac tetrodotoxin-insensitive voltage-dependent sodium channel. Proc Natl Acad Sci USA. 1992;89(2):554-8. ...
REST target genes were identified originally by the presence of a similar putative repressor-binding motif in genes encoding two neuronal-specific proteins, the voltage-dependent sodium channel and the synaptic protein, SCG10. Promoter fragments of these genes bound the REST repressor in vitro, and reporter genes containing the promoter were derepressed after loss of REST function in transient transfection analyses of non-neuronal cells (Chong et al., 1995; Schoenherr and Anderson, 1995; Schoenherr et al., 1996). These first studies suggested that REST-repressed genes were required for synaptic function, but whether other aspects of the neuronal phenotype were under REST control was not explored. Since that time, it has been suggested, primarily based on bioinformatics approaches, that many other synaptic proteins, as well as proteins involved in neurosecretion, are under REST control (Lunyak et al., 2002; Bruce et al., 2004; Sun et al., 2005; Johnson et al., 2006; Mortazavi et al., 2006; Wu and ...
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Wild specimens store batrachotoxin in glands in their skin, which can be fatal to humans in doses as small as 100 µg. The ... It has therefore been proposed that the frogs do not synthesize batrachotoxin themselves, but it is instead obtained from their ... In order to avoid self-intoxication the frogs have developed modified sodium channels to prevent the binding of batrachotoxin. ... Warnick, J.E.; Albuquerque, E.X.; Samsone, F.M. (1971). "The Pharmacology of Batrachotoxin. I. Effects on the Contractile ...
Rajchard, Josef (January 2009). "The batrachotoxins with a protective function in birds". Ethology Ecology & Evolution. 21 (1 ...
Its skin contains batrachotoxins, extremely potent neurotoxic alkaloids. When in contact with the skin, batrachotoxins seep ... Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of the food-based source, and such toxins ...
The birds probably do not produce batrachotoxin themselves. The toxins most likely come from the beetle genus Choresine, a part ... Batrachotoxin Toxic birds Birkhead, Tim (2012). Bird Sense: What it's like to be a bird. Bloomsbury Publishing. p. 120. ... a putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds". Proceedings of the ... contain powerful neurotoxic alkaloids of the batrachotoxin group (also secreted by the Colombian poison dart frogs, genus ...
Generally, batrachotoxin binds and permanently opens the sodium channels in nerve cells and can cause paralysis. The ... Ifrits excrete batrachotoxin into their feathers and skin in order to defend themselves against predators. ... Batrachotoxin Toxic bird BirdLife International (2012). "Ifrita kowaldi". IUCN Red List of Threatened Species. 2012. Retrieved ... "Batrachotoxin", Wikipedia, 2019-10-26, retrieved 2019-11-19 Dumbacher, John P.; Wako, Avit; Derrickson, Scott R.; Samuelson, ...
The batrachotoxins do not seem to have an effect on internal parasites such as Haemoproteus or the malaria-causing Plasmodium. ... The existence of resistance to batrachotoxins and the use of those toxins as chemical defences by several bird families have ... Dumbacher, J. P.; Spande, T. F.; Daly, J. W. (2000). "Batrachotoxin alkaloids from passerine birds: A second toxic bird genus ( ... There have also been experiments to test pitohui batrachotoxins on potential predators. They have been shown to irritate the ...
Batrachotoxin Heart failure Drug interaction Huang, C.; Zhang, X.; Ramil, J. M.; Rikka, S.; Kim, L.; Lee, Y.; Gude, N. A.; ...
... s are much weaker than batrachotoxins, ranging between 100 and 1000 times less poisonous. There are three different ...
Research is being conducted to determine medicinal uses for this batrachotoxin. As with all dart frogs, captive-raised ...
Some neurotoxins, such as batrachotoxin, are known to destroy synaptic vesicles. The tetanus toxin damages vesicle-associated ...
Batrachotoxins have been found to be poisonous to distantly related orders of insects, which suggests that batrachotoxins may ... One can only speculate on sources of avian batrachotoxins if they are not synthesized de novo. The occurrence of batrachotoxins ... The development of batrachotoxin in toxic birds has led to an advantage of these birds against ectoparasites, as they deter ... The search for batrachotoxins in organisms consumed by birds has yet to indicate an exogenous source. Stomach content studies ...
High concentrations of HTX have been demonstrated to have antagonistic effects on batrachotoxin. Histrionicotoxin is relatively ...
The toxic alkaloid batrachotoxin is only present in frogs found in the wild; after extended captivity, they lose their toxin, ... The most toxic of the many poisonous alkaloids these frogs contain (in glands in their skin) is batrachotoxin, alongside a wide ... A putative source for the Batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds". Proc. Natl. Acad. Sci ...
Kurosu, M.; Kishi, Y. (1998). "A Novel Example for Optical Resolution of Racemic Ketones Originating from Batrachotoxin ...
6-Chloronicotine Arrow poison Batrachotoxin (and closely related Homobatrachotoxin) Tetrodotoxin Phantasmidine Fitch, R. W.; ...
... batrachotoxin and aconitine. Experiments utilizing squid axonal membranes indicate that sodium channel binding likely occurs on ...
Batrachotoxin Cytotoxicity Multiple chemical sensitivity Nephrotoxicity Ototoxicity Penitrem A Excitotoxicity Toxicity Cunha- ...
High concentrations of HTX have been demonstrated to have antagonistic effects on batrachotoxin.[13] ...
It induces rapid block of the batrachotoxin (BTX)-activated sodium channels of the heart muscle and acts as antagonist to long- ... Procainamide is also known to induce a voltage-dependent open channel block on the batrachotoxin (BTX)-activated sodium ... Zamponi GW, Sui X, Codding PW, French RJ (December 1993). "Dual actions of procainamide on batrachotoxin-activated sodium ...
... batrachotoxin, in their feathers and skin. This combination of facts implies that the populations in these zones of overlap ...
Later, they learned that the feathers and other organs of the pitohui were found to contain batrachotoxin. Since then, six ...
Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of a food-based source, and such toxins do ... Batrachotoxin is only found in three poisonous frogs from Colombia (genus Phyllobates), a few birds from Papua New Guinea, and ... Batrachotoxin attacks the sodium channels of nerve cells, but the frog has special sodium channels the poison cannot harm. ... Since easily purchased foods are not rich in the alkaloids required to produce batrachotoxins, captive frogs do not produce ...
Scientists have not determined the batrachotoxin source for any species of the genus Phyllobates, although toxic birds from New ... a putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine birds". Proceedings of the ... Guinea likely get batrachotoxin from a small beetle of the family Melyridae. P. vittatus is a fairly large poison frog, ...
"Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic passerine ...
Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of a food-based source, and such toxins do ... Poison dart frog Many poison dart frogs secrete lipophilic alkaloid toxins such as allopumiliotoxin 267A, batrachotoxin, ... batrachotoxins). This poison prevents its victim's nerves from transmitting impulses, leaving the muscles in an inactive state ...
2004). "Melyrid beetles (Choresine): A putative source for the batrachotoxin alkaloids found in poison-dart frogs and toxic ...
... itself is an allosteric agonist for the action of batrachotoxin, and becomes even more effective when combined ...
The existence of resistance to batrachotoxins and the use of those toxins as chemical defences by several bird families have ... There have also been experiments to test pitohui batrachotoxins on potential predators. They have been shown to irritate the ... The hooded pitohui uses the same family of batrachotoxin compounds as the golden poison frog of Colombia. ... The batrachotoxins do not seem to have an effect on internal parasites such as Haemoproteus or the malaria-causing Plasmodium.[ ...
... batrachotoxin and many others. Kishi has also contributed to the development of new chemical reactions including the Nozaki- ...
Many poison dart frogs secrete lipophilic alkaloid toxins such as allopumiliotoxin 267A, batrachotoxin, epibatidine, ...
Batrachotoxin R is more toxic than related batrachotoxin A. Structural changes in nerves and muscles are due to a massive ... Batrachotoxin kills by permanently blocking nerve signal transmission to the muscles. Batrachotoxin binds to and irreversibly ... However, this limits the amount of batrachotoxin available for research as 10,000 frogs yielded only 180 mg of batrachotoxin. ... Batrachotoxin has been found in the four Papuan beetle species C. pulchra, C. semiopaca, C. rugiceps and C. sp. A, which are ...
batrachotoxin synonyms, batrachotoxin pronunciation, batrachotoxin translation, English dictionary definition of batrachotoxin ... batrachotoxin. Also found in: Medical, Wikipedia.. Related to batrachotoxin: saxitoxin. ba·tra·cho·tox·in. (bə-trăk′ə-tŏk′sĭn, ... Keywords: Batrachotoxin, radical mediated reaction, nBu3SnH, AIBN, alkynyl stannanes.. Towards the Synthesis of Batrachotoxin- ... Batrachotoxin - definition of batrachotoxin by The Free Dictionary https://www.thefreedictionary.com/batrachotoxin ...
Chemistry Alkynes Chemical properties Batrachotoxins Chemical research Chemical synthesis Research ... Towards the Synthesis of Batrachotoxin-Formation of Alkynyl Stannanes.(Report) by Journal of the Chemical Society of Pakistan ... The batrachotoxin family includes batrachotoxin 1, homo-batrachotoxin 2, batrachotoxinin-A 3 and pseudobatrachotoxin (unstable ... The famous neurotoxin batrachotoxin 1 is a member of a family of steroidal alkaloids called batrachotoxins. The structure of 1 ...
Batrachotoxin (BTX) not only keeps the voltage-gated Na(+) channel open persistently but also reduces its single-channel ... Irreversible block of cardiac mutant Na+ channels by batrachotoxin Channels (Austin). May-Jun 2007;1(3):179-88. doi: 10.4161/ ... Batrachotoxin (BTX) not only keeps the voltage-gated Na(+) channel open persistently but also reduces its single-channel ...
The pharmacology of batrachotoxin. VII. Structure-activity relationships and the effects of pH.. J E Warnick, E X Albuquerque, ... The pharmacology of batrachotoxin. VII. Structure-activity relationships and the effects of pH.. J E Warnick, E X Albuquerque, ... The pharmacology of batrachotoxin. VII. Structure-activity relationships and the effects of pH.. J E Warnick, E X Albuquerque, ... The effects of the depolarizing agent, batrachotoxin (BTX), and of various analogs were studied on rat phrenic nerve-diaphragm ...
batrachotoxin ligand page. Quantitative data and detailed annnotation of the targets of licensed and experimental drugs. ...
Batrachotoxin and alpha-scorpion toxin stabilize the open state of single voltage-gated sodium channels.. M E OLeary and B K ... Batrachotoxin and alpha-scorpion toxin stabilize the open state of single voltage-gated sodium channels.. M E OLeary and B K ... Batrachotoxin and alpha-scorpion toxin stabilize the open state of single voltage-gated sodium channels.. M E OLeary and B K ... Batrachotoxin and alpha-scorpion toxin stabilize the open state of single voltage-gated sodium channels. ...
The Batrachotoxin Receptor on the Voltage-Gated Sodium Channel is Guarded by the Channel Activation Gate. Hong-Ling Li, David ... The Batrachotoxin Receptor on the Voltage-Gated Sodium Channel is Guarded by the Channel Activation Gate. Hong-Ling Li, David ... The Batrachotoxin Receptor on the Voltage-Gated Sodium Channel is Guarded by the Channel Activation Gate. Hong-Ling Li, David ... Batrachotoxin (BTX), from South American frogs of the genusPhyllobates, irreversibly activates voltage-gated sodium channels. ...
Batrachotoxin (4) and homobatrachotoxin (6) were found only in feathers and not in skin. The levels of batrachotoxins varied ... The highest levels of batrachotoxins were generally present in the contour feathers of belly, breast, or legs in Pitohui ... batrachotoxin (4), batrachotoxinin-A 3-hydroxypentanoate (5), homobatrachotoxin (6), and mono- and dihydroxylated derivatives ... Batrachotoxins, including many congeners not previously described, were detected, and relative amounts were measured by using ...
3. Batrachotoxin. Flickr/Lwp Kommunikáció Weve all heard of South American Indians using venom-tipped blowpipes to hunt their ... Batrachotoxin kills by interfering with sodium ion channels in the cells of muscles and nerves, jamming them open so that they ... Maitotoxin is the most lethal of these substances, reckoned to have a LD50 about an order of magnitude less than batrachotoxin ... The most toxic, however, come from the skins of tiny frogs - and the deadliest of all is Batrachotoxin. ...
Batrachotoxin (1 μM) also induced contraction. Both effects were completely inhibited by the sodium channel blocker ... Vascular smooth muscle contraction induced by Na+ channel activators, veratridine and batrachotoxin. / Shinjo(H), Masayoshi; ... Batrachotoxin (1 μM) also induced contraction. Both effects were completely inhibited by the sodium channel blocker ... Batrachotoxin (1 μM) also induced contraction. Both effects were completely inhibited by the sodium channel blocker ...
Français : Un alkaloïde est une molécule organique à base dazote et possédant des effets pharmacologiques sur lêtre humain et sur dautres animaux ...
Interaction between batrachotoxin and yohimbine in cultured neuroblastoma cells. / Huang, L. M.; Ehrenstein, G.; Catterall, W. ... Interaction between batrachotoxin and yohimbine in cultured neuroblastoma cells. Biophysical journal. 1977 Jan 1;17(2):208a. ... title = "Interaction between batrachotoxin and yohimbine in cultured neuroblastoma cells",. author = "Huang, {L. M.} and G. ... Huang, L. M. ; Ehrenstein, G. ; Catterall, W. A. / Interaction between batrachotoxin and yohimbine in cultured neuroblastoma ...
Symptoms:Batrachotoxin. Lips and fingers were numb after handling the bird and wiping his mouth. These were minor symptoms and ... Diagnosis of Multiple Conditions:Batrachotoxin. Bill found a bird (pitohui) n Papua New Guinea Inside one of the feathers that ... Tests/Procedures Performed: Batrachotoxin. Symptoms:Tetrodotoxin. None simply because his symptoms didnt escalate further then ...
POISON: BATRACHOTOXIN. What is it? The poison found in the skin of golden poison frogs, batrachotoxin (bah-TRAY-ko-tox-in) gets ... How potent is it? On a weight basis, batrachotoxin is 250 times more powerful than the rat poison strychnine. ...
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. ...
Batrachotoxin is the nasty alkaloid used for poison darts. The molecule is the most potent non-peptide poisons known to man, ...
3. Batrachotoxin. Weve all heard of South American Indians using venom-tipped blowpipes to hunt their prey. Curare is the best ... Batrachotoxin kills by interfering with sodium ion channels in the cells of muscles and nerves, jamming them open so that they ... Maitotoxin is the most lethal of these substances, reckoned to have a LD50 about an order of magnitude less than batrachotoxin ... The most toxic, however, come from the skins of tiny frogs - and the deadliest of all is Batrachotoxin. ...
Batrachotoxin wirkung viagra. Renal abscesses or skin biopsy may be clues to viagra riscos da underlying disease process. ...
Gating kinetics of batrachotoxin-modified sodium channels in neuroblastoma cells determined from single-channel measurements. ... Huang L-Y, Moran N, Ehrenstein G. Gating kinetics of batrachotoxin-modified sodium channels in neuroblastoma cells determined ... Gating kinetics of batrachotoxin-modified sodium channels in neuroblastoma cells determined from single-channel measurements. ... Huang, L-Y, Moran, N & Ehrenstein, G 1984, Gating kinetics of batrachotoxin-modified sodium channels in neuroblastoma cells ...
Wild specimens store batrachotoxin in glands in their skin, which can be fatal to humans in doses as small as 100 µg. The ... It has therefore been proposed that the frogs do not synthesize batrachotoxin themselves, but it is instead obtained from their ... In order to avoid self-intoxication the frogs have developed modified sodium channels to prevent the binding of batrachotoxin. ... Warnick, J.E.; Albuquerque, E.X.; Samsone, F.M. (1971). "The Pharmacology of Batrachotoxin. I. Effects on the Contractile ...
Batrachotoxins are some of the most toxic natural substances known to man. Colombian arrow frogs are coated with the same ... Batrachotoxins also have significant effects on the heart muscles, causing abnormal rhythmic patterns and, eventually, cardiac ... The bird consumes beetles of the genus Choresine, which contain high levels of homobatrachotoxins, a type of batrachotoxin - ... By snacking on these poisonous beetles, the bird manages to assimilate the batrachotoxins into its skin and feathers. This ...
H]-Batrachotoxin Binding. [0102] The purpose of the present example is to determine the affinity of the tested compounds to [. ... H]-batrachotoxin. Non specific binding is determined in the presence of 0.3 mM veratridine. After 90 min incubation at 25° C., ... H]-batrachotoxin from its binding sites to rat cortical synaptosomes with potencies lying between that of bupivacaine (Ki=7.14± ... H]-batrachotoxin and various concentrations of test drugs (250 μl final volume). Non-specific binding is determined in the ...
The pharmacology of batrachotoxin. VII. Structure-activity relationships and the effects of pH. J E Warnick, E X Albuquerque, R ...
Previous Issue:Batrachotoxin (BTX). Of the Month Archives. Fernbank Science Center, 156 Heaton Park Drive, Atlanta, GA 30307 ...
Rights & permissionsfor article Model for the Action of Tetrodotoxin and Batrachotoxin . Opens in a new window. ...
batrachotoxin. Definition. most lethal toxin of any known animal (open nueronal Na channel and polarization cannot occur no ...
Batrachotoxin. *BCNU (Bischloroethyl Nitrosourea). *Behavioral Toxicology. *Belladonna Alkaloids. *Benchmark Dose. *Benfluralin ...
But the amount of batrachotoxins varied from bird to bird, which suggested that, instead of making batrachotoxins, the rubbish ... By eating the beetles, the pitohui was saturating its flesh with batrachotoxins-toxins that it had evolved resistance to but ... In 2004, the biologists traced the batrachotoxins to the Melyrid beetles the birds ate. These beetles, the New Guineans ... they found the feathers and skins were full of batrachotoxins, a dangerous chemical family of neurotoxins that the biologists ...
  • Although generally classified as a neurotoxin, batrachotoxin has marked effects on heart muscles. (wikipedia.org)
  • Batrachotoxin , isolated from frogs belonging to the genus Phyllobates, is a very potent neurotoxin and a steroidal alkaloid that has been found to block the Na+ channels in nerves and muscles resulting in arrhythmias or cardiac arrest leading to death. (thefreedictionary.com)
  • The famous neurotoxin batrachotoxin 1 is a member of a family of steroidal alkaloids called batrachotoxins. (thefreelibrary.com)
  • Meet the poison dart frog, which secretes a highly dangerous neurotoxin, called batrachotoxin, through its pores. (mentalfloss.com)
  • The steroidal neurotoxin (−)-batrachotoxin functions as a potent agonist of voltage-gated sodium ion channels (NaVs). (phys.org)
  • Just like it's amphibious friends, the little shrikethrush's skin, as well as its feathers, are coated with batrachotoxins-a type of neurotoxin. (sparknotes.com)
  • Batrachotoxin was discovered by Fritz Märki and Bernhard Witkop, at the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland, U.S.A. Märki and Witkop separated the potent toxic alkaloids fraction from Phyllobates bicolor and determined its chemical properties in 1963. (wikipedia.org)
  • They isolated four major toxic steroidal alkaloids including batrachotoxin, isobatrachotoxin, pseudobatrachotoxin, and batrachotoxinin A. Due to the difficulty of handling such a potent toxin and the minuscule amount that could be collected, a comprehensive structure determination involved several difficulties. (wikipedia.org)
  • According to experiments with rodents, batrachotoxin is one of the most potent alkaloids known: its intravenous LD50 in mice is 2-3 µg/kg. (wikipedia.org)
  • Batrachotoxin alkaloids from passerine birds: a second toxic bird genus (Ifrita ko-waldi) from New Guinea. (thefreedictionary.com)
  • Melyrid beetles (Choresine): a putative source for the batrachotoxin alkaloids found in poison dart frogs and toxic passerine birds. (thefreedictionary.com)
  • At the time, the alkaloids, called batrachotoxins , had been found in only one other source in nature, the Phyllobates poison dart frogs on the other side of the world--in Colombia and Panama. (thefreedictionary.com)
  • The bird consumes beetles of the genus Choresine , which contain high levels of homobatrachotoxins, a type of batrachotoxin - potent neurotoxic steroidal alkaloids. (medicalnewstoday.com)
  • The color pattern of D. silverstonei is a convergent autapomorphy showing only the most superficial resemblance to that of P. bicolor, and silverstonei lacks the potent batrachotoxin alkaloids of Phyllobates. (amnh.org)
  • Batrachotoxin and alpha-scorpion toxin stabilize the open state of single voltage-gated sodium channels. (aspetjournals.org)
  • The combined effects of batrachotoxin (BTX) and either scorpion (Leiurus quinquestriatus quinquestriatus) venom (LqqV) or alpha-scorpion toxin (alpha-LqqTX) purified from LqqV on single voltage-gated Na channels were studied in planar lipid bilayers. (aspetjournals.org)
  • Access to toxins and modified forms thereof (including saxitoxin, gonyautoxin, batrachotoxin, and veratridine) through de novo synthesis drives studies to elucidate toxin-receptor interactions and to develop new pharmacologic tools to study ion channel function in primary cells and murine pain models. (stanford.edu)
  • Their toxin, called batrachotoxin, forces open sodium channels on nerve cell membranes - with horrific results. (cosmosmagazine.com)
  • The poison dart frog has been known to scientists (and locals who have used its skin chemicals as a poison applied to the tips of blow-darts, which led to the name of the frog) for many years and several researchers have attempted to synthesize the batrachotoxin molecule in the toxin responsible for causing heart attacks in its victims. (phys.org)
  • Electrophysiological characterization of these molecules against NaV subtypes establishes the non-natural toxin enantiomer as a reversible antagonist of channel function, markedly different in activity from (−)-batrachotoxin. (phys.org)
  • Inactivation was voltage-dependent with a V h of −15mV, and was unaffected by veratridine, batrachotoxin (BTX), sea anemone toxin and scorpion ( Leiurus ) venom. (biologists.org)
  • The effects of the sodium channel activators veratridine and batrachotoxin on isolated rat aorta were investigated. (elsevier.com)
  • Batrachotoxin stimulated 22 Na + flux more effectively than did veratridine. (elsevier.com)
  • Lipid-soluble toxins such as batrachotoxin act directly on sodium ion channels involved in action potential generation and by modifying both their ion selectivity and voltage sensitivity. (wikipedia.org)
  • By eating the beetles, the pitohui was saturating its flesh with batrachotoxins-toxins that it had evolved resistance to but its predators hadn't. (slate.com)
  • 2016. Asymmetric synthesis of batrachotoxin: Enantiomeric toxins show functional divergence against Na V . Science . (icr.org)
  • It differs from batrachotoxin, tetrodotoxin, and saxitoxin, the only known nonprotein substances of greater toxicity, as well as from all toxins previously isolated from amphibia. (sciencemag.org)
  • The present study addresses model investigations of the actions of ligands of sodium channels, including tetrodotoxin and batrachotoxin, as well as local anesthetics. (ovid.com)
  • Birds in the genera Pitohui and Ifrita carry batrachotoxins , the same compounds found in some of the poison frogs of the Americas. (thefreedictionary.com)
  • Batrachotoxins, including many congeners not previously described, were detected, and relative amounts were measured by using HPLC-mass spectrometry, in five species of New Guinean birds of the genus Pitohui as well as a species of a second toxic bird genus, Ifrita kowaldi. (semanticscholar.org)
  • When the biologists examined pitohui specimens, they found the feathers and skins were full of batrachotoxins , a dangerous chemical family of neurotoxins that the biologists recognized from South American poison-dart frogs. (slate.com)
  • In 1992, Jack Dumbacher of the Smithsonian Institution in Washington DC discovered that the skin and feathers of Pitohui songbirds contain a poison called a batrachotoxin. (newscientist.com)
  • The hooded pitohui uses the same family of batrachotoxin compounds as the golden poison frog of Colombia. (wikipedia.org)
  • Congratulations to John Chapman for submitting batrachotoxin from the poison dart frog, Phyllobates terribili, as the poison used in the October 2009 "Lily Robinson and an Assassin's Tracks. (thefreedictionary.com)
  • Simply put, the patches I left for him were embedded with a highly lethal concentration of batrachotoxin from the poison-dart frog Phyllobates terribilis. (thefreedictionary.com)
  • Batrachotoxin (BTX), from South American frogs of the genus Phyllobates , irreversibly activates voltage-gated sodium channels. (aspetjournals.org)
  • Levels of batrachotoxin and lack of sensitivity to its action in poison-dart frogs (Phyllobates). (semanticscholar.org)
  • 2017. Single rat muscle Na+ channel mutation confers batrachotoxin autoresistance found in poison-dart frog Phyllobates terribilis . (icr.org)
  • This is a batrachotoxin, produced by frogs of the genus Phyllobates , one of the most powerful poisons in the world, especially that one of the Phyllobates terribilis, a species capable of killing 10 men with 1 milligram. (botanical-online.com)
  • My research has focused on the modification of sodium channel kinetics by Site 2 neurotoxins such as aconitine, lappaconitine, and batrachotoxin, as well as the block of sodium channels by a variety of local anesthetics and aminoglycosides. (murraystate.edu)
  • Batrachotoxin (BTX) is an extremely potent cardio- and neurotoxic steroidal alkaloid found in certain species of beetles, birds, and frogs. (wikipedia.org)
  • This frog is named because of its bright orange skin that is covered by a secretion of deadly alkaloid poison (batrachotoxins). (motherjones.com)
  • Their bright yellow skin is saturated in an alkaloid poison that contains batrachotoxins, which prevent nerves from transmitting nerve impulses and ultimately result in muscle paralysis. (aqua.org)
  • By snacking on these poisonous beetles, the bird manages to assimilate the batrachotoxins into its skin and feathers. (medicalnewstoday.com)
  • In 2004, the biologists traced the batrachotoxins to the Melyrid beetles the birds ate . (slate.com)
  • Batrachotoxins are naturally produced by certain species of frogs, beetles and birds. (thebeautybrains.com)
  • A] receptor ligand sites, the batrachotoxin site of the sodium channel (site 2) (Catterall et al. (thefreedictionary.com)
  • carried out first total synthesis of batrachotoxinin A from Wieland-Miescher ketone by utilizing intramolecular furan Diels-Alder reaction and oxy-Michael reaction [10] The work presented here is a reflection of our strategy towards the synthesis of steroidal skeleton of batrachotoxin 1 by the application of radical mediated cascade cyclization. (thefreelibrary.com)
  • The presented work highlights the attempts towards the synthesis of steroidal backbone of batrachotoxin 1. (thefreelibrary.com)
  • A medium-sized songbird with rich chestnut and black plumage, this species is one of the few known poisonous birds , containing a range of batrachotoxin compounds in its skin, feathers and other tissues. (wikipedia.org)
  • Batrachotoxin not only keeps voltage-gated sodium channels open, but it also reduces the single-channel conductance. (wikipedia.org)
  • Structurally-related chemical compounds are often referred to collectively as batrachotoxins. (wikipedia.org)
  • 5. Batrachotoxin: Frogs are cute except for maybe the poison dart frog that makes one of the most toxic compounds known. (personalcaretruth.com)
  • Members of Central and South American rainforest tribes hunt with darts dipped in batrachotoxins from dart-poison frog skin. (thefreedictionary.com)
  • Batrachotoxin is the nasty alkaloid used for poison darts. (thoughtco.com)
  • Batrachotoxin induces a massive release of acetylcholine in nerves and muscles and destruction of synaptic vesicles, as well. (wikipedia.org)
  • Batrachotoxin R is more toxic than related batrachotoxin A. Structural changes in nerves and muscles are due to a massive influx of sodium ions, which produces osmotic alterations. (wikipedia.org)
  • Batrachotoxin 1 tends to affect the nervous system by causing the irreversible opening of Na+ channels in the nerves causing a change in ion selectivity of the ion channel by increasing the permeability of the channel toward larger cations, which results in depolarization of nerves leading to failure of nerve impulse transmission [4]. (thefreelibrary.com)
  • Batrachotoxin kills by interfering with sodium ion channels in the cells of muscles and nerves, jamming them open so that they do not close. (businessinsider.com)
  • Batrachotoxin interferes with heart conduction, causing arrhythmias, extrasystoles, ventricular fibrillation and other changes which lead to cardiac arrest. (wikipedia.org)
  • Batrachotoxins also have significant effects on the heart muscles, causing abnormal rhythmic patterns and, eventually, cardiac arrest. (medicalnewstoday.com)
  • The influx of sodium into a nerve cell means it fires, but because batrachotoxin stops sodium channels from closing, the cell can't switch "off" again - causing paralysis, cardiac arrest and even death. (cosmosmagazine.com)
  • The most toxic, however, come from the skins of tiny frogs - and the deadliest of all is Batrachotoxin . (businessinsider.com)
  • Batrachotoxins are some of the most toxic natural substances known to man. (medicalnewstoday.com)
  • For batrachotoxin, the poison from the skin of poison dart frogs, it's 2-7 micrograms. (discovermagazine.com)
  • 1] The batrachotoxin family includes batrachotoxin 1, homo-batrachotoxin 2, batrachotoxinin-A 3 and pseudobatrachotoxin (unstable, converts to batrachotoxinin-A 3 on standing). (thefreelibrary.com)
  • Batrachotoxin binds to and irreversibly opens the sodium channels of nerve cells and prevents them from closing, resulting in paralysis. (wikipedia.org)
  • Batrachotoxin kills by permanently blocking nerve signal transmission to the muscles. (wikipedia.org)
  • And because it also deadens nerve endings, batrachotoxin has potential as an ingredient in anesthetics. (mentalfloss.com)
  • Playing around with different forms of these molecules allows them to explore even more about the channel function - and exploiting the differences often generates medical treatments - maybe an antidote to the deadly natural form of batrachotoxin. (cosmosmagazine.com)
  • https://dx.doi.org/10.2305/IUCN.UK.2017-2.RLTS.T55261A85887593.en. (wikipedia.org)
  • The original assay of impulse blockade was complemented by experiments testing the competitive displacement of radiolabeled batrachotoxin ( 3 H-BTX) from the Na + channels in rat brain synaptosomes. (asahq.org)
  • Batrachotoxins are highly unpleasant and frequently lethal. (thefreedictionary.com)
  • P. aurotaenia is one of the most lethal species of the poison dart frogs, which is attributed to their storage and release of batrachotoxin from cutaneous granular glands scattered throughout the frogs' bodies. (wikipedia.org)
  • Wild specimens store batrachotoxin in glands in their skin, which can be fatal to humans in doses as small as 100 µg. (wikipedia.org)
  • Daly and Myers found that they could use the presence of one alkaloid, batrachotoxin , to show that several species had a common ancestor. (thefreedictionary.com)
  • So Logan and his crew wondered if the mirror-image form of batrachotoxin (which isn't found in nature) might also bind to sodium channels - and if so, with what effect. (cosmosmagazine.com)
  • It has therefore been proposed that the frogs do not synthesize batrachotoxin themselves, but it is instead obtained from their environment. (wikipedia.org)
  • Batrachotoxin in the PNS produces increased permeability (selective and irreversible) of the resting cell membrane to sodium ions, without changing potassium or calcium concentration. (wikipedia.org)
  • Batrachotoxin also alters the ion selectivity of the ion channel by increasing the permeability of the channel toward larger cations. (wikipedia.org)
  • Batrachotoxin (BTX) irreversibly binds to the Na+ channels which causes a conformational change in the channels that forces the sodium channels to remain open. (wikipedia.org)
  • Dual actions of procainamide on batrachotoxin-activated sodium channels: open channel block and prevention of inactivation. (abcam.com)
  • Huang, L-Y , Moran, N & Ehrenstein, G 1984, ' Gating kinetics of batrachotoxin-modified sodium channels in neuroblastoma cells determined from single-channel measurements ', Biophysical Journal , vol. 45, no. 1, pp. 313-322. (utmb.edu)
  • In order to avoid self-intoxication the frogs have developed modified sodium channels to prevent the binding of batrachotoxin. (wikipedia.org)
  • Voltage dependence of intramembrane charge movement and conductance activation of batrachotoxin-modified sodium channels in frog node of Ranvier. (rupress.org)
  • But the amount of batrachotoxins varied from bird to bird, which suggested that, instead of making batrachotoxins, the rubbish bird was getting its rubbish elsewhere. (slate.com)
  • When the mass spectrum and NMR spectrum of batrachotoxin and the batrachotoxinin A derivatives were compared, it was realized that the two shared the same steroidal structure and that batrachotoxin was batrachotoxinin A with a single extra pyrrole moiety attached. (wikipedia.org)
  • In fact, batrachotoxin was able to be partially hydrolyzed using sodium hydroxide into a material with identical TLC and color reactions as batrachotoxinin A. The structure of batrachotoxin was established in 1969 through chemical recombination of both fragments. (wikipedia.org)
  • Today, poison dart frogs are endangered and collecting natural batrachotoxin is restricted. (cosmosmagazine.com)
  • Here we report concise asymmetric syntheses of the natural (−) and non-natural (+) antipodes of batrachotoxin, as well both enantiomers of a C-20 benzoate-modified derivative. (phys.org)