ENDOTHELIN-INDUCED RENAL VASOCONSTRICTION AND INCREASE IN CYTOSOLIC CALCIUM IN RENAL VASCULAR SMOOTH-MUSCLE CELLS

This study was designed to investigate the effects of the potent vasoconstrictor, endothelin, on renal hemodynamics in rats in vivo, and in addition, to measure intracellular calcium ion ([Ca2+].) in monolayers of renal vascular smooth muscle cells in culture using the fura-2 method. Endothelin (1 nmol) dramatically decreased renal blood flow from 7.0±0.5 ml/min to 2±6±1±0 ml/min, whereas it increased mean arterial pressure from 100±2 mmHg to 113±7 mmHg. These alterations persisted over 20 minutes in conscious and almost unrestrained rats. Endothelin (10-8 -10-7 mol/l) immediately increased [Ca2+]i, although the increase by endothelin (10-9 mol/l) was relatively slow. The increase persisted in the presence of 1 mmol/l extracellular calcium. In the absence of extracellular calcium, only a small, transient increase of [Ca2+]i was observed. These results indicate that endothelin produces renal vasoconstriction and increases the [Ca2+]i in cultured renal vascular smooth muscle cells. The latter effect is dependent mainly on extracellular calcium. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.