Effects of Angiotensin on Plasma Electrolyte Concentrations in Rabbits and in Man

Abstract

1. The effects of an intravenous infusion of angiotensin on plasma electrolytes were examined in normal, adrenalectomized and nephrectomized groups of rabbits and in normal man. Rabbits were given 1 pg kg-I min-' and human subjects 0.008-0.030 pg kg-' min-' of angiotensin.2. In normal rabbits, angiotensin increased arterial and venous plasma K within 2 min by 0.8 and 0.4 mmol I-' respectively, some hyperkalaemia persisting for 30-60 min. After 60 rnin arterial plasma Na decreased by 3.8 mmol I-' and C1 by 2.4 mmol 1-I. Arterial blood pH increased 0.04 units after 15 min, and arterial plasma Mg and Ca rose slightly after 2 min. Pressor response was 20-28 mmHg.3. In adrenalectomized and nephrectomized rabbits, arterial plasma K rose within 2 min by 2.6 and 3.8 mmol 1-' respectively. Arterial plasma Na fell after 60 min in both groups, and also after 2 min in nephrectomized animals. Venous plasma K and Na showed similar although less marked changes. Changes in plasma Mg, Ca and blood pH were not significant. Pressor response in both groups exceeded that in normal rabbits. 4. In man, a sustained rise of 0-2-0.3 mmol 1-' occurred in arterial plasma K during angiotensin infusion. Arterial blood pH rose 0.01 units after 15 min. Pressor response was 12-15 mmHg.5. It was concluded that plasma electrolyte levels may change during angiotensin administration in rabbits and man, and that these changes may influence interpretation of physiological actions of angiotensin.

Role of angiotensin II in potassium-mediated stimulation of aldosterone secretion in the dog.

“…Captopril, through its effect on eliminating angiotensin II formation, may have retarded the expected rise in plasma potassium concentration after potassium infusion. This is consistent with the demonstration by Healy et al (34) that angiotensin II administered to the rabbit and to humans causes plasma potassium levels to increase. An effect of captopril to curtail potassium as a stimulus by preventing potassium levels to increase sufficiently was considered in the present study.…”

Proceedings of the Physiological Society, 16‐17 July 1982, Cambridge Meeting: Communications

“…and g.f.r., the mechanism responsible for the natriuresis remains unclear. The possibility of a direct action of angiotensin on proximal tubular sodium reabsorption has been shown previously (Harris & Young, 1977) and is supported by the study of Healy & Elliott (1971) who showed that angiotensin-induced natriuresis in rabbits occurs even when the increase in blood pressure is prevented by haemorrhage.…”

Influence of angiotensin II on the concentration of arterial plasma electrolytes in anaesthetized sheep

“…A similar view has been expressed by Healy et al (1974), who first demonstrated this important action of the octapeptide, in conscious rabbits.…”

“…Except for the dose-response studies, the dose of angiotensin I or II was given on a weight-related basis, where W was the weight of the sheep in kilograms, and the concentration (pg/ml) ofthe decapeptide was 5/8 H^and that of the octapeptide 1/2 W. The concentrations achieved in unit time were approximately equimolar in individual sheep and similar to those reported previously (see Healy, Elliott & Harrison, 1974;. In contrast, the dose of catecholamines was not related to the weight of the animal.…”