RENAL-FUNCTION IN SPONTANEOUSLY HYPERTENSIVE RATS WITH INSULIN-EXACERBATED HYPERTENSION

This study tests the hypothesis that in spontaneously hypertensive rat s (SHR), insulin decreases natriuresis and diuresis and thereby contri butes importantly to the hypertensive response to exogenous insulin ad ministration. Seven week old SHR were given daily subcutaneous injecti ons of either insulin (mixture of 5 U/Kg regular and 10 U/Kg NPH) or v ehicle (isotonic saline). Within one week of treatment, systolic arter ial pressure (SAP) was significantly higher in the insulin, compared t o saline, treated SHR (184.2 +/- 2.5 vs. 158.3 +/- 4.0 mm Hg). However , twenty-four hour sodium and fluid excretion and the natriuretic and diuretic responses to an intravenous saline load were not affected eit her before or after the insulin-induced exacerbation of hypertension i n SHR. Insulin treatment did not affect glomerular filtration rate, ef fective renal blood flow, or fractional excretion of Naf or fluid. The refore, our data do not support a major role for sodium and fluid rete ntion in the insulin-induced exacerbation of hypertension in SHR.