The Reactivity of Isolated Veins to Electrical Stimulation

Abstract

A simple method is described to follow the capacity changes of isolated venous segments of the turtle during graded electrical stimulation. The reaction of the isolated veins to increasing frequencies of subpramaximal stimuli can be graphically represented by a typical S-shaped frequency/volume curve. On repeated stimulation of the same preparation a gradually increasing sensitivity was observed in function of time. From results with adrenolytic drugs, reserpine, bretylium and ganglion blocking drugs it appears that the observed venoconstriction depends on release of catecholamines from tissue stores through stimulation of sympathetic nerve terminals remaining in the vascular wall. This way of electrical stimulation may permit graded venomotor tone in vitro.