Electrical and mechanical events through activation of muscarinic receptor in the smooth muscle of guinea-pig vas deferens.

Electrical and mechanical responses of the guinea-pig vas deferens to exogenous acetylcholine (ACh) were observed by means of a single sucrose-gap method. ACh at various concentrations evoked a contraction consisting of two components. The initial component seemed to be independent of a depolarization, while the second one was dependent on it. All ACh responses were abolished by Ca removal from the external solution. The results suggest the existence of a pathway by which ACh even at low concentrations causes a Ca influx without potential changes.