[Pharmacological studies on supersensitization (IV). Site and mode of action of cocaine to potentiate acetylcholine in isolated tracheal preparation of rat (author's transl)].
Effects of cocaine on acetylcholine-induced contracture of isolated rat tracheal preparation were determined. The sensitivity of the preparation to acetylcholine but not methacholine and carbachol was increased by cocaine. The maximum responses induced by choline esters were not augmented by cocaine. The potentiation of acetylcholine was remarkable in calcium-deficient medium and cocaine augmented acetylcholine-contracture of the preparation suspended in calcium-free Tyrode solution. Calcium-contracture of the preparation susspended in isotonic 60 mM- or 100 mM-K+ Locke-Ringer solution was not augmented by cocaine. Extrapolating the time course of decrease in acetylcholine-contracture in calcium-free Tyrode solution, rates of calcium movement from and into calcium-stores were determined and it was found that cocaine did not change the calcium-content and rate of calcium-efflux but the rate of calcium-uptake was apparently increased with cocaine. The contribution of anticholinesterase activity of cocaine to potentiation of acetylcholine appeared negligible and the affinity of acetylcholine-receptor to acetylcholine and atropine was not changed with cocaine. Thus, cocaine increases acetylcholine-induced calcium-release and potentiates acetylcholine-contracture of isolated rat tracheal preparation.
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D066298:In Vitro Techniques; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014132:Trachea / Q000187:drug effects
D008688:Methacholine Compounds; D001285:Atropine; D002217:Carbachol; D010830:Physostigmine; D003042:Cocaine; D000109:Acetylcholine; D002118:Calcium