Effects of synthetic atrial natriuretic peptide on renal function and renin release in acute experimental heart failure.

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Abstract
Studies were performed in anesthetized control dogs (n = 6) and in dogs (n = 6) with acute low-output heart failure produced by inflation of a balloon in the thoracic inferior vena cava. Studies were designed to determine the effects of synthetic atrial natriuretic peptide on renal function and renin release in this acute high-renin, sodium-retaining preparation. Intrarenal infusion of synthetic atrial natriuretic peptide (0.3 micrograms X kg-1 X min-1) resulted in decreases in arterial pressure and renal blood flow in both groups. Glomerular filtration rate increased in both low-output (delta + 10.7 +/- 3.1 ml/min) and control (delta + 8.7 +/- 2.9 ml/min) groups. Fractional lithium excretion, a marker of proximal tubule reabsorption, also increased in both low-output (delta + 12.0 +/- 4.6%) and control (delta + 14.3 +/- 5.0%) groups. Renin secretory rate decreased in the low-output group from 852.8 +/- 183.0 to 149.5 +/- 73.7 ng/min and in the control group from 308.5 +/- 84.5 to 44.5 +/- 27.5 ng/ml. Intrarenal infusion of atrial natriuretic peptide resulted in an attenuated increase in both urinary sodium excretion (delta + 42.3 +/- 10.7 vs delta + 201.2 +/- 37.9 mueq/min) and fractional excretion of sodium (delta + 0.48 +/- 0.13% vs delta + 2.85 +/- 0.45%) in the low-output as compared with the control group. Our studies demonstrate that administration of synthetic atrial natriuretic peptide results in an increase in glomerular filtration rate and a decrease in proximal tubule reabsorption, as estimated by lithium excretion, in both control dogs and those with acute low-output heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)