The effect of carbachol and alpha-bungarotoxin on the frequency of miniature endplate potentials at the frog neuromuscular junction.
The effects of an acetylcholine analogue, carbachol (CCh), and a purified irreversible nicotinic antagonist, -bungarotoxin (BTX), on the frequency of the miniature endplate potentials (mEPPs) at the neuromuscular junction of the frog were tested at 20 and 10 C. CCh (5 10-6 m) reduced the frequency of mEPPs to about 60 %; this reduction was not affected by 1 10-7 g ml-1 BTX. BTX also reversibly decreased the mEPP frequency by 40 %, but not in the presence of CCh or in Ringer solution with 0 or 8 mM Ca2+. The present data show that BTX, which inhibits a class of nicotinic ACh receptors, does not block the decrease of mEPP frequency evoked by CCh and can itself suppress the frequency of spontaneous quantal release.
Bukharaeva
E
E
Kazan Medical University and Kazan Institute of Biophysics and Biochemistry of the Russian Academy of Sciences, Butlerov Str. 49, Kazan, Tatarstan, Russia.
Ipatova
T
T
Nikolsky
E E
EE
Vyskocil
F
F
D000818:Animals; D002038:Bungarotoxins / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D004594:Electrophysiology; D066298:In Vitro Techniques; D009045:Motor Endplate / Q000187:drug effects* / Q000502:physiology*; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology*; D011895:Rana ridibunda; D013696:Temperature
D002038:Bungarotoxins; D018679:Cholinergic Agonists; D002217:Carbachol; D002118:Calcium