[Functional significance of the instability of neuromuscular relations in the vascular wall].

In isolated preparations of the rabbit ear artery, the contractile response to a single electrical stimulus and its latency were studied at different degrees of stretching. Contractile responses were compared in direct and indirect stimulations of the vessel's smooth muscle at different temporal interrelationships between the stimulus and the stretching process. The contractile response was found to augment in indirect stimulation within a certain stretch area of the vascular ring whereas its latency was found to shorten. The direct stimulation of the desympathised vessel left latency the same whereas the contractile response started to diminish at a lesser stretching. The comparison of contractile responses of the artery's smooth muscle in indirect and direct stimulations suggests that, with reduction of neuro--muscular distances, an automatic increase of adrenergic effects on the vascular wall occurs. The significance of this phenomenon for vascular tone control is discussed.