Control of the interrenal gland of the freshwater turtle Chrysemys picta in vivo and in vitro

Abstract

Interrenal function was studied in the freshwater turtle Chrysemys picta by competitive protein-binding analysis of plasma corticosterone in vivo and corticosterone synthesis by interrenal cell suspensions in vitro. Although circulating levels of corticosterone in intact, unanesthetized turtles (0.22 μg/100 ml) are lower than in other vertebrates, hypophysectomy reduced and ACTH increased these levels. Synthetic ACTH 1–24 was more potent in vivo than pACTH, and in vitro 10–1000 pg/ml gave a log dose increase in corticosterone production. Interrenal cell suspensions were also responsive to crude homogenates of turtle pituitary. Bleeding was a potent stimulus to interrenal secretion in vivo mediated in part via endogenous corticotropin release.