Angiotensin II dependency of vascular resistance in the untouched kidney of renal hypertensive rats.

Renal hemodynamics following administration of the angiotensin II antagonist Saralasin were studied in untouched kidney of 11 two-kidney hypertensive rats and in kidneys of 7 control rats using an electromagnetic flowmeter. Renal blood flow (RBF) in controls averaged 6.2 +/- (SD) 1.7 vs. 5.2 +/- 0.9 ml/min/g kidney weight in the hypertensive group (n.s.). Renal vascular resistance (RVR) was significantly increased in untouched kidneys: 2.6 +/- 0.5 vs. 1.8 +/- 0.4 dyn . sec . cm-5 . 10(6) . g kidney weight-1. Following Saralasin infusion mean arterial blood pressure decreased significantly more in hypertensive rats. RBF increased by 24% in untouched kidneys vs. 12% in controls (p < 0.05), indicating a 34% decrease of RVR in hypertensive rats vs. 18% (p < 0.005) in controls. These results indicate that the increased RVR in untouched kidneys is highly dependent on circulating angiotensin II, which may reduce the antihypertensive role of the untouched kidney.