On the requirement for calcium during the steroidogenic effect of ACTH.

Abstract

The requirement for calcium during the steroidogenic effect of both ACTH and adenosine-3’,5’-cyclophosphate (cyclic-AMP) has been studied. Upon incubating rat adrenal sections, deletion of calcium from the incubation media decreased the steroidogenic effectiveness of both ACTH and cyclic-AMP by approximately 40-50%. Leucine incorporation into protein was diminished to a comparable degree, and there was a direct correlation between inhibition of steroidogenic responsiveness and inhibition of amino acid incorporation into protein. Whereas protein synthesis was inhibited by deleting calcium, incorporation of orotic acid into RNA was increased, and it would appear that the inhibitory effects of deleting calcium are not simply due to a generalized inhibition of cellular functions which require energy (ATP) production. The present results suggest that a major reason for the calcium requirement during ACTH and cyclic-AMP action is the maintenance of optimal adrenal protein synthesis, which in turn is thought to ...