Regulation of rat renal (Na+ + K+)-adenosine triphosphatase activity by triiodothyronine and corticosterone.

The present study concerns the effects of corticosterone and T3 on renal cortical and outer medullary NaK-ATPase activities in the rat. The results show that corticosterone increases cortical and outer medullary NaK-ATPase activities when administered as either a single or multiple doses. Corticosterone and T3 are known to enhance NaK-ATPase activity. We investigate the possibility of interaction between the effects of corticosterone and T3 on renal NaK-ATPase activity. Our studies indicate that corticosterone and T3 regulate renal cortical NaK-ATPase activity via parallel independent pathways, and that corticosterone appears to regulate medullary NaK-ATPase activity without participation by thyroid hormone.