The Role of Renin in the Exaggerated Natriuresis of Hypertension

TLDR: The enhanced capacity of the renin-unresponsive hypertensive subjects to excrete a salt load suggests either a functionally significant degree of extracellular fluid volume expansion or a direct role for renin in the natriuresis accompanying volume expansion.

Abstract: Hypertensive patients were classified according to their plasma renin response when challenged by the potent diuretics, ethacrynic acid (50 mg IV), or furosemide (40 mg IV), into renin-unresponsive and renin-responsive groups In the latter plasma renin activity rose by at least 05 ng of angiotensin/ml/hr after the diuretic The response to volume expansion with 2 L of isotonic saline infused over 60 min was then studied Peak rate of sodium excretion after saline loading was 994±186 µEq/min in the renin-unresponsive group and peak urine flow was 119 ± 21 ml/min In the renin-responsive hypertensives peak sodium excretion was 448 ± 149 µEq/min and peak urine flow was 54 ± 15 ml/min Both the sodium excretion and urine flow responses were significantly higher (P < 005) in the renin-unresponsive group The degree of saline-induced diuresis and natriuresis was not related to the preexisting level of aldosterone production Plasma renin changed little in either group during saline infusion but tended to