CHRONIC EFFECTS OF SYNTHETIC ENDOTHELIN ON BLOOD-PRESSURE AND SODIUM-EXCRETION IN RATS

Continuous infusion of endothelin at a rate of 60 μg/kg/day into the jugular vein of rats via osmotic minipumps induced a significant increase in systolic blood pressure, but did not induce any significant changes in urine volume and urinary sodium excretion, compared to those in vehicle-infused rats. When 6 mg/kg/day of benidipine, a newly developed calcium channel blocker, was administered simultaneously with 60 μg/kg/day of endothelin, the systolic blood pressure of conscious rats rose on Day 1 to only 137.0 ± 2.4 mm Hg (P <.05) compared to the rise to 163.8 ± 4.7 mm Hg when endothelin alone was infused. The antihypertensive effect of benidipine was sustained. The present results suggest that endothelin can act as a circulating hormone. In addition, they clearly demonstrate that the calcium channel blocker attenuates the elevation of blood pressure induced by endothelin. © 1990 by the American Journal of Hypertension, Ltd.