Isolation of aldosterone-stimulating factor (ASF) and its effect on rat adrenal glomerulosa cells in vitro

A protein fraction has been isolated from normal human urine which upon chronic administration produced hypertension in rats. The hypertension is associated with retention of sodium and increased circulating aldosterone. The protein fraction has been purified to homogeneity, and its molecular weight has been determined to be 26,134 daltons by equilibrium ultracentrifugation. The compound has been identified to be clearly different from ACTH, angiotensin II, and beta-lipotropin. It stimulated aldosterone production from rat glomerulosa cells in vitro in a dose-dependent fashion from 10(-9) to 10(-4)M with a maximum stimulation at 10(-7) where a fourfold increase was obtained during 2 hours of incubation. Removal of some carbohydrate moieties by insoluble neuraminidase caused a twofold increase in aldosterone production in vitro. The protein fraction has been named "aldosterone-stimulating factor" or "ASF." Further studies are in progress to define its physiological role.