Abstract
Summary
Quinidine given in small intravenous doses appears to act at the prejunctional area with no apparent action on the postjunctional membrane as judged by a lack of effect on the ACh-evoked twitch. However, larger intra-arterial doses of quinidine produce a neuromuscular blockade which has the characteristics of the postjunctional depolarizing type. No evidence of muscle membrane depression is present since quinidine does not depress twitch tension elicited from direct muscle stimulation of a curarized cat. Edrophonium potentiated the neuromuscular blockade produced by intra-arterial quinidine, while calcium was an inconsistent antagonist.
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