Arterial blood pressure, urine flow rate, and plasma and urine electrolytes were measured in the aglomerular goosefish (L. americanus) before, during, and after the intravenous infusion of angiotensin II (from 5 to 280 ng/min.kg body wt). Increases in arterial blood pressure were directly related to the logarithm of the angiotensin infusion rate (r = 0.62, P less than 0.005). Angiotensin also increased urine flow from 0.676 +/- 0.065 to 0.755 +/- 0.068 ml/h.kg body wt (P less than 0.005) and Na excretion from 41.0 +/- 5.5 to 54.4 +/- 7.0 mumol/h.kg body wt (P less than 0.001). In 17 of the 19 fish infused with angiotensin the diuretic and natriuretic effects were directly related to the logarithm of the infusion rate (r = 0.44, P less than 0.04 and r = 0.51, P less than 0.02, respectively). There was no relationship between the pressor and the diuretic or natriuretic effects of angiotensin II. These results are consistent with inhibitory effects of angiotensin on solute transport by aglomerular tubules.
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