[Effect of cholinergic compounds on spontaneous quantal mediator release at the neuromuscular synapse of the frog].
The action of cholinergic drugs on spontaneous quantal transmitter release has been investigated in the frog sartorius muscle. Acetylcholine and carbacholine decreased the miniature end-plate potential frequency. These presynaptic effects had no dependence on the potassium concentration in the bath solution. Nicotinic agonists--nicotine, tetramethylammonium and suberyldicholine had a similar effect, while muscarinic agents--methylfurmetide, oxotremorine and F-2268 (L- and D-stereoisomers) did not affect the transmitter release. The presynaptic effects of carbacholine and acetylcholine were abolished neither by atropine nor by d-tubocurarine and bensohexonium. It is suggested that there are nicotinic receptors on the frog motor nerve terminals that modify spontaneous quantal transmitter release and differ pharmacologically from nicotinic end-plate, ganglionic and presynaptic receptors of higher vertebrates.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D004347:Drug Interactions; D005730:Ganglionic Blockers / Q000494:pharmacology; D005731:Ganglionic Stimulants / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D010277:Parasympathomimetics / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D011896:Rana temporaria; D009435:Synaptic Transmission / Q000187:drug effects*
D005730:Ganglionic Blockers; D005731:Ganglionic Stimulants; D010277:Parasympathomimetics; D000109:Acetylcholine; D011188:Potassium
Vliianie kholinergicheskikh soedineniĭ na spontannoe kvantovoe osvobozhdenie mediatora v nervno-myshechnom sinapse liagushki.