Metabolism of aldosterone by the splanchnic organs of the dog.

Abstract

The role of the splanchnic organs of the dog in aldosterone metabolism was investigated. 3H-aldosterone was infused at a constant rate. Following equilibration, simultaneous blood samples were drawn from an artery, hepatic vein, superior mesenteric vein, splenic vein and renal vein. The concentration of free 3H-aldosterone and its tetrahydroaldosterone glucuronide conjugate were determined in each plasma sample. The concentration of aldosterone-18-glucuronide failed to reach equilibrium during the time period of the experiment. From these values percent extractions were calculated. For free aldosterone the mean percent extractions for the hepatic vein, superior mesenteric vein and splenic vein were: 84.7% ± 5.4 (SE), 53.0% ± 4.2 (SE) and 15.8% ± 5.7 (SE) respectively. These results indicate that there is net uptake of free aldosterone not only by the splanchnic bed as a whole, but also by the intestine and spleen. For tetrahydroaldosterone glucuronide the mean percent extractions for the hepatic vein, superior mesenteric vein and splenic vein were: -57.9% ±23.6 (SE), 18.9% ±7.6 (SE) and 17.4% ± 5.6 (SE) respectively. These results indicate that there is net production of tetrahydroaldosterone glucuronide by the splanchnic bed as a whole, but net uptake by the intestine and spleen. From these results it is concluded that 1) the intestine and spleen contribute significantly to the total splanchnic metabolism of aldosterone, 2) that the liver is the major, and probably the only site of splanchnic production of tetrahydroaldosterone glucuronide. (Endocrinology89: 1309, 1971)