[Influence of colchicine on the effects of acetylcholine and pilocarpine on isolated ventricle of the ammocete Lampetra planeri (Bloch)].

Colchicine inhibits the positive chronotopic effects of acetylcholine and of pilocarpine of the isolated ammocoete heart ventricle. This positive chronotropic effect is due to a release of catecholamines from the chromaffin cells of the lamprey heart. The action of colchicine, which does not result from its curare-like effect, suggests that acetylcholine induces release of catecholamines by exycytosis.