The effect of parathyroid hormone on the distribution of osteoclasts
Talmage, Roy V.
Master of Arts
Calcium removal from bone of the amphibian, R. catesbiana, was studied utilizing the technique of peritoneal lavage. Calcium changes in the lavage fluid were compared in parathyroidectomized and control frogs at two temperatures (4°C. and 22°C.). A histological comparison between parathyroid glands of lavaged animals and non-lavaged controls was made. In addition, the distribution and frequency of osteoclasts in the various bones of this frog were examined to relate their occurrence with the state of activity of the parathyroid glands. The results of these studies suggest that parathyroid function as related to its influence on bone follows the same pattern in the frog as has been reported previously for the rat. Both control and parathyroidectomized frogs were capable of supplying calcium from bone to peritoneal fluid as demonstrated by the lavage procedures. The frog could not, however, maintain this process indefinitely, for in all cases extremely erratic removal was noted after six hours of continuous lavage. Whether this was due to a change in parathyroid function or to the adverse results of prolonged lavage procedures could not be determined. The effect of the reduction of body temperature on these processes was not as clear cut. There was no difference in the amount of calcium removed in control or parathyroidectomized frogs maintained and lavaged at 4°C. However, this amount was significantly lower than the parathyroidectomized value at 22°C. The data for the removal of total calcium could best be interpreted as the reduction of an enzymatic process by parathyroidectomy and a further reduction to a base level by placing the animal in the cold. The osteoclast studies indicated that a relationship between osteoclasts and parathyroid function similar to that in mammals exists in these amphibians. The apparent exhaustion produced in the parathyroid tissue of lavaged frogs indicated that the lavage procedures produced a marked, though probably temporary, increase in endogenous parathyroid hormone production.