High water intake combined with low sodium intake abolishes the antidiuretic effect of angiotensin II in conscious dogs.
1. We studied post-prandial changes in renal function in dogs adapted to either low or high sodium intake with and without concomitant post-prandial infusion of angiotensin II. Six trained dogs were exposed to diets containing either 0.5 or 14.5 mmol Na+ day-1 kg-1 body weight (low or high sodium respectively). They were studied from 20 min before to 4 h after food intake. In half of the experiments a physiological dose of angiotensin II (4 ng min-1 kg-1 body weight) was administered after food intake for four post-prandial hours. The water intake was high and equal on both diets (91 ml day-1 kg-1 body weight). 2. On a high-salt diet post-prandial sodium excretion and urine volume increased considerably above fasting values. This post-prandial increase was attenuated when angiotensin II was infused (post-prandial sodium excretion was 31% +/- 3% of intake without versus 10% +/- 1% with angiotensin II, post-prandial urine volume was 22% +/- 2% without versus 8% +/- 1% with angiotensin II, P < 0.05). Post-prandial increases in glomerular filtration rate and fractional sodium excretion were attenuated during angiotensin II infusion in dogs on a high-salt diet. 3. On a low-salt diet post-prandial sodium excretion remained low with or without angiotensin II infusion, whereas urine volume increased post-prandially, and this increase was greater when angiotensin II was administered (40% +/- 3% versus 34% +/- 2% of intake, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Kaczmarczyk
G
G
Klinik für Anaesthesiologie and operative Intensivmedizin, UKRV-Charlottenburg, Freie Universität Berlin, Germany.
Boemke
W
W
Zahrei-Fard
D
D
Braun
H
H
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D003243:Consciousness; D004231:Diuresis / Q000187:drug effects*; D004285:Dogs; D004326:Drinking; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007668:Kidney / Q000502:physiology; D009318:Natriuresis / Q000187:drug effects; D012982:Sodium, Dietary / Q000008:administration & dosage*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D012982:Sodium, Dietary; D014662:Vasoconstrictor Agents; D000804:Angiotensin II