Acute effects of angiotensin II on renal haemodynamics and excretion in conscious dogs.
The effects of a 60-min intravenous infusion of angiotensin II (A II; 4 or 20 ng A II/min/kg body weight) on renal blood flow (RBF; electromagnetic flow transducer, control value 19-25 ml/min/kg), glomerular filtration rate (GFR; control value 4.2-5.0 ml/min/kg), mean arterial blood pressure, sodium excretion, water excretion, and plasma A II and plasma aldosterone concentrations were examined in 6 chronically instrumented female conscious beagle dogs kept on three different dietary sodium intakes (SI): SI 0.5 or SI 2.5 mmol Na/kg/day or SI 4.5 mmol Na/kg/day plus an oral saline load prior to the experiment SI 4.5(+) dogs. Four nanograms A II decreased RBF and GFR in SI 4.5(+) dogs without changing the filtration fraction (FF%); in SI 0.5 dogs the RBF decreased, and the FF% increased. Twenty nanograms A II decreased RBF and increased FF% in all dietary protocols, less in SI 4.5(+) dogs. The mean arterial blood pressure increased in all dietary protocols by 10-15 mm Hg (4 ng A II) and 32-37 mm Hg (20 ng A II). Sodium and water excretions decreased by 32 and 46%, respectively, in SI 4.5(+) dogs at both doses of A II. The plasma aldosterone concentration increased in all but one protocol: 4 ng A II, SI 4.5(+) dogs. It is concluded that when A II plasma concentrations are most likely borderline to pathophysiological conditions (up to an average of 370 pg/ml), the GFR is less decreased than the RBF. This phenomenon also can be observed at lower plasma A II concentrations (average 200 pg/ml), when the renin-angiotensin system had been previously moderately activated.
Keil
J
J
Arbeitsgruppe für Experimentelle Anästhesie, Universitätsklinikum Rudolf Virchow, Freie Universität Berlin.
Lehnfeld
R
R
Reinhardt
H W
HW
Mohnhaupt
R
R
Kaczmarczyk
G
G
D000450:Aldosterone / Q000097:blood; D000804:Angiotensin II / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001798:Blood Proteins / Q000032:analysis; D004285:Dogs; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006400:Hematocrit; D006439:Hemodynamics / Q000187:drug effects; D007275:Injections, Intravenous; D007668:Kidney / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000097:blood / Q000652:urine; D012079:Renal Circulation / Q000187:drug effects*; D012964:Sodium / Q000097:blood / Q000494:pharmacology / Q000652:urine*; D014556:Urine / Q000032:analysis
D001798:Blood Proteins; D000804:Angiotensin II; D000450:Aldosterone; D012964:Sodium; D011188:Potassium