Hypercalcemia induced by prostaglandin E2 in thyroparathyroidectomized but not intact rats

Prostaglandin E2 was infused into thoracic aorta of thyroparathyroidectomized (TPTX) and intact rats. Circulating calcium increased significantly in the TPTX group by 30 minutes and reached an increment of 1.5 +/- 0.21 mg/dl (x +/- SE, p less than .001) by 90 minutes. No calcium increments were observed in the intact rats. It is postulated that prior failures to demonstrate hypercalcemia during PGE2 infusion may have been due to calcitonin counterregulation.