The interaction between atrial natriuretic peptides and angiotensin II in controlling sodium and water excretion in the rat.

摘要

1. The present study was designed to determine how the natriuretic and diuretic actions of atrial natriuretic peptides were modulated by circulating angiotensin II. 2. In sodium pentobarbitone-anaesthetized rats, administration of bolus doses of atriopeptin III (1000 ng kg-1) had no effect on blood pressure, renal blood flow, or glomerular filtration rate but caused reversible increases (all P less than 0.001) in urine flow, of 53.9 +/- 14.4 microliters kg-1 min-1, absolute sodium excretion, of 13.4 +/- 2.9 mumol kg-1 min-1 and fractional sodium excretion of 3.26 +/- 0.74%. Similar effects were seen following a second dose of the atriopeptin III. 3. Following blockade of the renin-angiotensin system with captopril (900 micrograms kg-1 h-1), control levels of blood pressure and haemodynamics were unchanged but there were significant (all P less than 0.001) increases in urine flow, from 39.96 +/- 5.05 to 88.70 +/- 8.41 microliters kg-1 min-1, absolute sodium excretion, from 8.35 +/- 1.08 to 21.62 +/- 1.62 mumol kg-1 min-1 and fractional sodium excretion, from 3.82 +/- 0.23 to 5.34 +/- 0.32%. Under these conditions, atriopeptin III-induced increases in urine flow (110.2 +/- 8.7 versus 43.9 +/- 6.2 microliters kg-1 min-1) absolute (24.0 +/- 1.8 versus 9.3 +/- 1.2 mumol kg-1 min-1) and fractional (5.16 +/- 0.24 versus 2.08 +/- 0.33%) sodium excretions were significantly (P less than 0.001) greater.(ABSTRACT TRUNCATED AT 250 WORDS)