Effect of Renal Injury on the Activity of Enzymes Preferentially Hydrolyzing Parathyroid Hormone

Abstract

The activity of enzymes preferentially hydrolyzing parathyroid hormone at pH 8.5 was markedly decreased in the supernatant of rat kidney homogenate centrifuged at 600g 24hr after the intraperitoneal injection of 0.5g/kg Na-Sulfacetylthiazole (SAT). The content of plasma 125I-PTH 30 min after the intravenous injection in SAT-treated rats was greater than that in control animals. The content of 125I-PTH and non-PTHbound 125I was marked ly decreased in the SAT-treated rat kidney as compared with that of controls but there was no difference in the ratio of 125I-PTH to non-PTH-bound 125I in the kidney between SAT-treated rats and control ones. The delayed disappearance of plasma 125I-PTH in SAT-treated rats than in controls might be related to the impairment of inactivation of PTH by the kidney due to the decrease of renal PTH'ase activity induced by SAT treatment.