Effects of a Body Cast on Aldosterone and Sodium Excretion in Dogs With Experimental Ascites

Abstract

The effects of application of a plaster body cast upon aldosterone and sodium excretion were studied in eight dogs with experimental ascites. In association with an increase in intra-abdominal pressure, aldosterone output declined and sodium excretion increased. In three dogs net sodium loss occurred and in three animals the low sodium-potassium ratio of fecal electrolyte excretion characteristic of increased circulating aldosterone returned to normal. The increased sodium excretion was not attributable to elevated GFR as GFR was frequently unchanged or reduced. Furthermore, no consistent alterations in plasma sodium or potassium, T-1824 dye space in plasma or arterial pressure were detected. It is suggested that aldosterone secretion was decreased as a result of an increase in intra-abdominal pressure which inhibited filtration of fluid into the peritoneal cavity to form ascites.