The effect of veratrine on 24Na uptake by frog sartorius muscle in hypertonic media.

The effect of veratrine on 24Na uptake by sartorius muscles incubated in hypertonic media has been studied. 1. 0.1 mM veratrine increases 24Na uptake in muscles incubated even in different hypertonic solutions (normal Ringer + 300 mM sucrose or glucose or 150 mM NaCl). 2. 0.05 mM curare inhibits the 24Na uptake increasing effect of veratrine in hypertonic solution 3. 0.1 mM ouabain, whether in isotonic or hypertonic solution, does not influence the resting 24Na uptake, and does not decrease the 24Na uptake increasing effect of veratrine in isotonic media; however, in hypertonic solution it inhibits the 24Na uptake increasing effect. 4, 5 X 10(-8) M tetrodotoxin blocks completely the 24Na uptake enhancing effect of veratrine both in isotonic and in hypertonic Ringer's solution. 5. It is suggested that the sites of action of the 24Na uptake increasing effect of veratrine are the neural structures in muscle, in hypertonic media.