1. Transmembrane potentials (Em) of vascular muscle cells in caudal arteries in vitro from one-kidney, one-clip hypertensive and one-kidney, sham-clipped normotensive rats were measured.
2. The Em recorded in hypertensive rats was significantly lower (depolarized) than that recorded in normotensive control rats.
3. Boiled plasma supernatants from hypertensive rats depolarized the muscle cells in normotensive caudal artery but had no effect on muscle cells in arteries from hypertensive rats.
4. Boiled plasma supernatants from normotensive control rats had no effect on the Em of either animal.
5. Ouabain depolarized muscle cells of the normotensive artery only and the magnitude of depolarization induced was nearly the same as that produced by the supernatant from the hypertensive animals.
6. These data suggest that a ouabain-like humoral substance may play a role in the pathophysiology of one-kidney, one-clip hypertension through a voltage-dependent mechanism.