Abstract
Summary
The effect of porcine thyrocalcitonin has been studied in the rat using an experimental system which produces a high rate of bone resorption. The technique utilized was that of peritoneal lavage with a calcium- and phosphate-free rinse. The hormone extracted from thyroid glands was administered either as a single injection following the third hour of lavage, or as multiple injections administered at intervals of 2 to 3 hrs. Thyrocalcitonin produced a marked suppression in removal rates of calcium, phosphate and their radioisotopes. It was also effective in animals parathyroidec-tomized 12 hours prior to lavage, though the recovery in these animals was slower than in those with intact parathyroid glands.
Also, in all cases, the removal of radioactive isotopes administered 2 or more weeks prior to use of the animals was suppressed to a greater degree than those recently administered. Magnesium removal was not affected by administration of thyrocalcitonin. These studies support the conclusion that the primary action of the new hormone is related to its ability to rapidly reduce bone resorption. It is also suggested that while thyrocalcitonin inhibits parathyroid action, the two hormones are not solely antagonistic to each other.
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