Abstract
The activity of an enzyme preferentially hydrolyzing parathyroid hormone in rat kidney homogenate was evaluated at various levels of parathyroid hormone activity and calcium metabolism. Transient hypercalcemia, hypocalcemia, increase and absence of parathyroid hormone for a short duration did not influence the enzyme activity. However, the enzyme activity showed a slight but significant decrease in parathyrordectomized rat in which sustained hypocalcemia was produced for 8 days. Hypercalcemia induced by the administration of dihydrotachysterol for 4 weeks provoked an increase in the enzyme activity.
