Effect of angiotensin II on the endolymphatic sac direct current potential

The effect of angiotensin II (ANG II), known as a potent pressor hormone, on the endolymphatic sac direct current potential (ESP) was examined. Intravenous administration of ANG II produced a reversible decrease in the ESP at doses exceeding 0.1 microgram/kg. The effect of ANG II on the ESP was dose-dependent at doses of less than 3 micrograms/kg with a saturated effect at doses of more than 3 micrograms/kg. The maximum reduction of the ESP produced by ANG II was 33.8 +/- 2.9% (m +/- SE, n = 6) of the original amplitude. The action of ANG II on the ESP was blocked by propranolol (beta-adrenergic antagonist). The mechanism underlying the action of ANG II on the ESP is discussed.