Abstract
Two adult dogs, which had been subjected to repeated (7 times each) filling and emptying of the peritoneal space (dextose, 2.5%-NaCl, 0.9% solution, 100 cc per kg) during the preceding 3 weeks, were treated as indicated in Fig. 1. The purpose of the repeated filling and evacuation of the peritoneum, particularly during the 24 hours preceding the injection of parathyroid hormone, was to determine whether the removal, by this means, of diffusible calcium from the blood would influence the response to parathyroid hormone.∗
In Dog 19 (18 kg), a total of 183 mg, and in Dog 20 (18 kg), 201 mg of calcium was removed in the peritoneal fluid in the 24 hours immediately preceding the intramuscular injection of parathyroid hormone. No food and only distilled water were allowed during the experimental period.
Three points of interest are revealed by these data.
(1) Under certain conditions, the administration of parathyroid hormone may result in hypocalcemia. That these animals were not refractory to the hormone was indicated by the fact that changes occurred in the serum and peritoneal fluid magnesium which were identical with those observed in a series of cases in which hypercalcemia was produced by the hormone. 1
(2) A fall in serum calcium may be accompanied by a fall in the peritoneal fluid calcium. This is of importance in view of the doubt as to whether the concentration of calcium in the fluid is capable of changing, and especially of decreasing rapidly simultaneously with corresponding changes in the diffusible fraction of serum calcium.
(3) An actual and significant increase in “diffused” calcium may occur following parathyroid hormone administration with a constant (Dog 19) or a falling (Dog 20) serum calcium concentration.
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