Antagonism voltage dependence

Voltage-dependent L-type calcium receptors have four distinct binding sites near the pore for calcium flux. By binding to these receptor sites calcium channel antagonists block the inward calcium current through the L-type channels and antagonize increases in heart rate, SA/AV node conduction, and heart contraction. Calcium... 

Pharmacology and Mechanism of Action. Topiramate is a sulfamate-substituted monosaccharide that has multiple modes of action involving voltage-dependent sodium channels, GABA receptors, and antagonism of a-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid (AMPA) subtype glutamate receptors. ... 

Riluzol antagonizes glutamatergic transmission via different mechanisms indirect blockade of NMDA receptors (modification of receptor phosphorylation status), inhibition of excitatory amino acid release by an agonist effect on an unknown receptor bound to protein G or interaction with voltage-dependent sodium channels (depressor effect on neurones with a high tonic activity spontaneously). The pharmacological properties of the compound can be explained by these mechanisms anti-seizure, anti-ischaemia, antagonism of MPTP cytotoxicity [201]. 

ACh overload causes bradycardia, slows conduction in AV, prevents hydrolysis [Ca2+]tM ACht Lowers ATP, cAMP ATPase inhibition 1k,atp1 (activated), AP shortened pHL Na /H exchanget, [ATP]L [Mlot, reduces Zk, by increasing rate of deactivation, shifts voltage dependence of activation to more positive potentials, gKt [K+lot effect on velocity of propagation, inexcitability Prolongs AP, [Na+lt, Na / M-ATPase antagonized DAD enhanced difference for a, p receptors Adenylate cyclase activation... 

Tetrodotoxin and saxitoxin, which block the voltage-dependent sodium channels, prevent and actually reverse batrachotoxin-elicited depolarizations. The blockade by tetrodotoxin occurs at a different channel site than that at which batrachotoxin acts. Classical anesthetics, however, would appear to antagonize the action of batrachotoxin through competition for the binding site (50 and references therein). Local anesthetics have been shown to block but perhaps not reverse the action of batrachotoxin in squid axon (79), rat diaphragm (77), eel electroplax (55), frog nerve 160, 765), synaptosomes (706, 179), and neuroblastoma cells (50, 755, 756). 

---