PARATHYROID FUNCTION AS STUDIED BY CONTINUOUS PERITONEAL LAVAGE IN NEPHRECTOMIZED RATS1

Abstract

The influence of the parathyroids on the ability of bone of nephrectomized rats to supply Ca to the extracellular spaces was studied by means of continuous peritoneal lavage. Isotonic (but Ca and phosphate-free) rinses were allowed to equilibrate in the peritoneal cavity of each rat for varying periods of time, and then removed for analysis. Parathyroidectomy, after the peritoneal lavage had commenced, produced a drop in both Ca and citric acid levels of the wash within half an hour. However, the parathyroidectomized animals were able to maintain a continuous and constant Ca output from bone after the initial drop. While differences between control and parathyroidectomized animals could be seen even in the 10-minute equilibration periods, calculations of rate of removal of Ca indicated that the most likely effect of the hormone of the parathyroids was concerned with the level of equilibration of calcium. During the maintenance of the higher Ca levels in the extra-cellular compartment, bones of animals with intact parathyroids showed a marked increase in the number of osteoclasts after as little as 6 hours of continuous peritoneal lavage. Parathyroidectomized rats showed no such increase.