Increased Aldosterone Secretion Following Acute Constriction of the Inferior Vena Cava1

Abstract

Effects of acute constriction of the thoracic inferior vena cava (7 dogs) and of the abdominal inferior vena cava above the adrenals (4 dogs) on aldosterone, corticosterone and Porter-Silber steroid secretion in adrenal vein plasma were studied. Three dogs with thoracic caval constriction received dextran intravenously to maintain or to increase plasma volume. After 3 control determinations 30 minutes apart, 6-8 measurements were made at similar intervals during the experimental period. Following thoracic caval constriction alone, aldosterone secretion increased within 30 minutes and reached levels 2-4 times greater than the average control rates of 0.008-0.024 [mu]g/minute; corticosterone and Porter-Silber steroid output remained unchanged or decreased. Plasma volume was reduced. However, similar increases in aldosterone secretion occurred despite increased vascular volume secondary to infused dextran in 3 other animals with thoracic caval constriction. Two of 4 dogs with abdominal caval constriction showed increased aldosterone secretion; this occurred only after marked caval constriction and large sustained increments in venous pressure. The data demonstrate increased aldosterone secretion following acute constriction of the inferior vena cava above or below the hepatic veins and irrespective of changes in vascular volume.