Long-term hypotensive and renal effects of atrial natriuretic peptide.

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Abstract
The present study was designed to examine the short-term and long-term effects of increased plasma levels of atrial natriuretic peptide on the glomerular filtration rate, sodium excretion, and arterial pressure. Intravenous infusion of synthetic atrial natriuretic peptide (2 micrograms/kg/bolus, 50 ng/kg/min continuous infusion) for 45 minutes in six conscious dogs increased plasma levels of immunoreactive atrial natriuretic peptide from 69 +/- 10 to 233 +/- 14 pg/ml. Short-term increases in plasma levels of atrial natriuretic peptide increased the glomerular filtration rate from 53 +/- 15 to 82 +/- 16 ml/min and increased sodium excretion from 74.4 +/- 32.6 to 146.9 +/- 38.1 microEq/min. Mean arterial pressure decreased slightly, from 88 +/- 3 to 83 +/- 3 mm Hg, whereas no changes occurred in plasma renin activity (2.0 +/- 0.6 to 1.6 +/- 0.8 ng of angiotensin I per milliliter per hour) or plasma aldosterone concentration (6.9 +/- 2.3 to 8.1 +/- 3.9 ng/dl). To determine whether the short-term effects of atrial natriuretic peptide on the glomerular filtration rate and sodium excretion lead to a sustained reduction in mean arterial pressure, atrial natriuretic peptide (50 ng/kg/min) was infused intravenously for 5 days in six conscious dogs. Long-term infusion increased plasma levels of immunoreactive atrial natriuretic peptide from 27 +/- 5 to 292 +/- 31 pg/ml. The infusion caused only a transient increase in sodium excretion and had no significant long-term effect on the glomerular filtration rate. Mean arterial pressure decreased from 90 +/- 3 to 74 +/- 3 and 75 +/- 4 mm Hg by Days 4 and 5 of the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)