Action of L-epinephrine on the renin-aldosterone system and on urinary electrolyte excretion in man

Abstract

The effect of L-epinephrine infusions (0.5–6.5 μg/min for up to 24 hr) in recumbency, on the renin-aldosterone system was studied in normal volunteers on diets containing 200 mEq sodium. Urinary sodium excretion was increased, potassium excretion was decreased, aldosterone excretion was suppressed while blood pressure and heart rate were minimally affected by epinephrine (1 μg/min). Inulin and para-aminohippurate clearances changed transiently and slightly during epinephrine infusions over 10 hr in normal subjects. In separate experiments, epinephrine lowered serum K, raised serum Na, raised plasma renin activity and, usually, lowered plasma aldosterone concentrations. There was an excellent correlation between epinephrine-induced changes in serum K and plasma aldosterone concentrations ( r = +0.85, p < 0.001). Significant dose-response relationships were found between L-epinephrine infusion rates of 0.5–6.5 μg/min and observed serum K concentrations. We conclude that L-epinephrine infusions at rates probably well within the physiological range, induce hypokalemia (by increased cellular uptake of K) which lowers aldosterone secretion despite concomitant elevation of PRA and causes natriuresis for up to 24 hr.