ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. The possible interactions between the renal effects of atrial natriuretic peptide (ANP) and angiotensin II (All) were studied in normal sodium-replete human subjects. Recent investigations have suggested that ANP inhibits the pressor and volume-retaining effects of activation of the renin-angiotensin system. Thus, ANP may attenuate the effects of All on renal haemodynamics or tubular transport.2. ANP (0.1 μg/kg per min, 60 min) was intravenously infused into eight normal human subjects with and without pretreatment with enalapril (20 mg, per oral), an inhibitor of the converting enzyme, and during infusion of All (10 mg/kg per min).3. ANP infusion alone caused increases in the urine volume (from 96 ± 23 to 229 ± 44 mL/h, P 〈 0.05) and urinary sodium excretion (from 11.5 ± 1.6 to 20.9 ± 4.2 mEq/h, P 〈 0.05). These changes were accompanied by an increase in the glomerular filtration rate (from 127 ± 9 to 158 ± 9 mL/min, P 〈 0.05). ANP infusion after enalapril administration lowered the mean blood pressure (from 76 ± 2 to 71 ± 3 mmHg, P 〈 0.05) to a level similar to that observed during ANP infusion alone (from 84 ± 2 to 74 ± 2 mmHg, P 〈 0.01), but did not result in a significant diuresis (from 139 ± 23 to 174 ± 51 mL/h) or natriuresis (from 19.7 ± 2.5 to 14.3 ± 3.4 mEq/h, P 〈 0.05). This combined treatment with a converting enzyme inhibitor and ANP reduced both the glomerular filtration rate (160 ± 9 to 141 ± 10 mL/min) and the renal plasma flow (from 775 ± 49 to 570 ± 45 mL/min, P 〈 0.01).4. The antinatriuretic effects of exogenous All were reversed by superimposed ANP infusion (urinary sodium excretion: from 4.8 ± 1.0 to 24.3 ± 5.2 mEq/h, P 〈 0.01). Under these conditions, the glomerular filtration rate increased (from 114 ± 6 to 156 ± 7 mL/min, P 〈 0.05) to levels similar to those observed with ANP infusion alone. In addition the increased tubular sodium reabsorption induced by All was inhibited by concomitant ANP infusion (fractional proximal tubular sodium reabsorption: from 90.7 ± 3.5 to 80.3 ± 16.6%, P 〈 0.05, fractional post-proximal tubular sodium reabsorption: from 91.5 ± 9.8 to 87.6 ± 8.8%, P 〈 0.05).5. These results suggest that ANP interacts with endogenous All particularly in the glomerulus, to cause a diuresis and natriuresis, and also suggest that ANP inhibits All-induced tubular sodium reabsorption.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1989.tb01533.x
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