AJP - Heart and Circulatory Physiology, Vol 251, Issue 4 880-H883, Copyright © 1986 by American Physiological Society

ARTICLES

Effect of atriopeptin III on hematocrit and volemia of nephrectomized rats

J. P. Fluckiger, B. Waeber, G. Matsueda, B. Delaloye, J. Nussberger and H. R. Brunner

The effect of a synthetic atrial natriuretic peptide (atriopeptin III) on blood pressure, heart rate, and hematocrit was investigated in conscious, nephrectomized (n = 6), and sham-operated (n = 6) rats. Atriopeptin III infusion (1 microgram/min iv for 30 min) decreased mean blood pressure to a similar extent in nephrectomized [from 122 +/- 5 to 108 +/- 3 (SE) mmHg; P less than 0.01] and in sham-operated rats (from 124 +/- 4 to 103 +/- 2 mmHg; P less than 0.01), whereas it had no significant effect on heart rate. Hematocrit rose similarly in nephrectomized (from 45 +/- 1 to 49 +/- 1%; P less than 0.01) and in sham-operated rats (from 46 +/- 1 to 50 +/- 1%; P less than 0.001). Infusion of the vehicle of atriopeptin III to nephrectomized rats (n = 7) did not change any of these parameters. Plasma volume and red cell mass of nephrectomized rats infused with atriopeptin III was measured by use of radiolabeled albumin and erythrocytes, respectively. A plasma volume contraction of approximately 10% (P less than 0.01) was observed, whereas red cell mass did not change. In an additional group of nephrectomized rats (n = 6), Na nitroprusside was infused intravenously at a rate of 2 micrograms/min for 30 min. Na nitroprusside reduced mean blood pressure from 127 +/- 4 to 106 +/- 3 mmHg (P less than 0.001), but hematocrit remained unchanged (46 +/- 1% before vs. 45 +/- 1% after infusion). In four anesthetized rats with both kidneys and the spleen removed atriopeptin III still raised the hematocrit.(ABSTRACT TRUNCATED AT 250 WORDS)