Effects of synthetic atrial natriuretic factor (ANF) on renin-aldosterone axis in the conscious newborn calf.
The effects of synthetic atrial natriuretic factor (ANF) on the renin-aldosterone axis were studied in fifteen 4-7 day-old male milk-fed calves divided into 3 groups of 5 animals each. Synthetic ANF intravenous (i.v.) administration (1.6 micrograms/kg body wt over 30 min) induced a transient significant fall in plasma renin activity (from 2.5 +/- 0.3 to 1.7 +/- 0.3 ng angiotensin l/ml/h; P less than 0.05) but failed to reduce basal plasma aldosterone levels in the first group of animals. Administration (i.v.) of angiotensin II (AII) (0.8 micrograms/kg body wt for 75 min) was accompanied by a progressive fall in plasma renin activity (from 2.2 +/- 0.3 to 0.8 +/- 0.1 ng angiotensin l/ml/h; P less than 0.01) and by an increase in plasma aldosterone levels (from 55 +/- 3 to 86 +/- 5 pg/ml; P less than 0.01) both in the second and the third groups; addition of ANF to AII infusion (AII: 0.5 mu/kg body wt for 45 min; AII: 0.3 micrograms/kg body wt and ANF 1.6 micrograms/kg body wt during 30 min) in the third group did not modify plasma renin activity or AII-stimulated plasma aldosterone levels when compared to the AII-treated group. These findings show that in the newborn calf ANF is able to reduce plasma renin activity but fails to affect basal and AII-stimulated plasma aldosterone levels, suggesting that the zona glomerulosa of the newborn adrenal cortex is insensitive to a diuretic, natriuretic and hypotensive dose of the atrial peptide.
Amadieu
M
M
U.A. C.N.R.S. 1123, I.N.R.A. Theix, Ceyrat, France.
Giry
J
J
Barlet
J P
JP
D000450:Aldosterone / Q000032:analysis*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002417:Cattle; D008297:Male; D012083:Renin / Q000032:analysis; D012084:Renin-Angiotensin System / Q000187:drug effects*
D000804:Angiotensin II; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D012083:Renin