Splanchnic Extraction and Clearance of Aldosterone in Subjects with Minimal and Marked Cardiac Dysfunction1

Abstract

The metabolic clearance rate (MCR) and splanchnic extraction of aldosterone were measured by analyzing hepatic and peripheral venous plasma after a continuous infusion of the tritiated hormone. In 9 subjects with minimal cardiac dysfunction (cardiac outputs in the normal range), the MCR of aldosterone was 1330±140 (SE) liters of plasma per day and the splanchnic extraction was 89 ±3 (SE)%. In 7 subjects with marked cardiac dysfunction (cardiac outputs subnormal or rt. ventricular systolic blood pressures > 100 mm Hg), both the MCR [800±65 (SE) liters plasma/day] and splanchnic extraction [71±5 (SE)%] were significantly lower. Using ¹³¹I Rose Bengal, hepatic blood flow and splanchnic aldosterone clearance were measured simultaneously in most of the subjects. Extrasplanchnic clearance of the hormone was found to be significant but a minor component (17 ±4%) of the total metabolic clearance rate in subjects with both minimal and marked cardiac dysfunction. Some of the subjects with subnormal cardiac indices had normal hepatic blood flows and a high proportion of the cardiac output flowing through the liver. The splanchnic extraction tended to be lower in these subjects. The lowered MCR of aldosterone in heart failure was due to either decreased extraction or hepatic plasma flow or both. Plasma concentrations of aldosterone may be raised in subjects with cardiac dysfunction and normal secretion rates.