Hypercalciuric Response to Acute Parathyroidectomy in Rats: Effects of Adrenalectomy

Abstract

Parathyroidectomy in the rat, whether performed surgically or by cautery, was followed by an increase of urinary Ca during the 4-hr, period immediately following the operation. Prior adrenalectomy abolished the response, a fact which necessitates a re-evaluation of the widely held hypothesis that parathyroid hormone increases reabsorption of Ca by a direct action on the renal tubule. Neither prior adrenal demedullation nor treatment with the adrenergic blocking agent, phenoxybenzamine, blocked the hypercalciuric response. It is concluded that the adrenal medulla is not the major factor associated with the hypercalciuric response. The possible role of the adrenal cortex is discussed. Incidental evidence was uncovered which suggested that thyrocalcitonin, endogenously released by cautery, might increase Ca clearance to a limited extent.