Effect of Parathyroid Extract on Renal Function

Abstract

The increase in plasma inorganic P concn. previously attributed to the action of intraven.-admd. parathyroid extract has been shown to be dependent upon exptl. conditions rather than to the effects of parathyroid extract. Parathyroid extract injd. intraven. in dogs decreases plasma inorganic phosphate concn. and increases endogenous creatinine clearance and the excretion of phosphate; the latter is, at least in part, consequent upon the increased phosphate filtered through the glomerulus. Subcut.-admd. parathyroid extract also lowers the plasma inorganic phosphate concn. and produces a phosphaturia, but has no effect on creatinine clearance; its action appears to depend on a diminished tubular reabsorption of phosphate. The factor raising glomerular filtration rate (GFR) and renal plasma flow and the factor raising blood Ca are both non-dialyzable and completely destroyed by incubation with pepsin. Since subcut. injd. parathyroid extract produces large rises in Ca concn. but has little or no effect on the GFR, the renal hemodynamic effect is not considered to be essential to the action of the hypercalcemic factor. These effects may be due to separate entities. The factor in parathyroid extract which raises the arterial blood pressure of rats has been shown to be separate from the renal hemodynamic and Ca raising activities of such preparations. This factor is dialyzable and not affected by incubation with pepsin.