EFFECTS OF ADRENALECTOMY ON THE RESPONSE OF MICE TO PARATHYROID HORMONE AND THYROCALCITONIN

¹ Department of Zoology, University of Maryland, College Park, Maryland

⁴⁵Ca and ³²P were administered to male CD-1 mice seven hours prior to the measurement of total Ca, inorganic phosphorus (P₁) and specific activities in serum collected from total trunk drainage after decapitation. Fifteen units of Lilly parathyroid extract (PTE), administered to parathyroidectomized mice at time same time as the isotopes, significantly raised Ca, lowered P₁ and lowered the specific activities (by stimulating the mixing of stable Ca and P₁ from bone with the serum). Adrenalectomy (ADX) changed the effects of PTE by reducing the calcemic rise and abolishing the change in specific activities of both isotopes (but had no effect on the drop in P₁). Cortisol given to ADX mice returned the hypercalcemic action of PTE to normal. When crude thyrocalcitonin was given two hours prior to sacrifice, ADX did not block the thyrocalcitonin-induced hypocalcemia in parathyroidectomized mice. In conclusion, while ADX did not alter the hypocalcemic effect of thyrocalcitonin, ADX did reduce the calcemic response to PTE and abolished the effect of PTE on the mixing of stable Ca and P from bone with the serum pools.