Effects of Bufalin on Renal Venous Outflow, Urine Flow and Natriuresis in the Anesthetized Dog
Recent studies suggest that the endogenous digitalis-like substance (DLS) implicated in the pathogenesis of low renin hypertension in animals and humans may be a steroidal dienolide derivative. One of these derivatives, bufalin (aglycone), inhibits Na+,K+-ATPase (1) and has recently been shown in our laboratory to have some of the physiological characteristics expected of a DLS (2). For example, infusion of bufalin into the brachial artery of the anesthetized dog increases vascular resistance and blocks K+ vasodilation while it potentiates norepinephrine vasoconstriction (Fig. 1). When bufalin is administered intravenously in the dog, increases in heart rate, dP/dt, and arterial blood pressure ensue (Fig. 2). In some animals (3/7) post-infusion natriuresis and diuresis occurs. Intravenous infusion in the rat likewise produces increases in blood pressure, heart rate, and dP/dt, and marked diuresis, natriuresis and kaliuresis (3) during and post-infusion. The present study in the anesthetized dog has been designed to examine the mechanism for the post-infusion natriuresis and diuresis seen with bufalin.
KeywordsUrine Flow Sodium Excretion Toad Skin ATPase Inhibitor Renal Venous Blood
Unable to display preview. Download preview PDF.
- 1.Brownlee AA, Lee G, Maills IH. Marked inhibition of canine renal Na+,K+-ATPase by a bufodienolide but weak natriuretic activity in the rat. J Physiol 390: 94P, 1987.Google Scholar
- 3.Pamnani MB, Eliades DC, Schooley JF, Haddy FJ. Effects of bufalin, a Na+,K+-ATPase inhibitor, on cardiovascular hemodynamics and renal excretory function in rats. Circulation 78 (Suppl II): II - 369, 1988.Google Scholar
- 6.Blaustein MP. Sodium ions, calcium ions, blood pressure regulation, and hypertension: A reassessment and a hypothesis. Am JPhysiol 232: C165 - C173, 1977.Google Scholar
- 7.Pamnani MB, Harder DR, Huot SJ, Bryant HJ, Kutyna FA, Haddy FJ. Vascular smooth muscle membrane potential and a ouabainlike humoral factor in one-kidney, one clip hypertension in rats. Clin Sci 63: 31s - 33s, 1982.Google Scholar