Selective Effects of Insulin on Hepatic Epinephrine Responsive Adenyl Cyclase Activity

It was previously shown that prednisolone markedly and selectively reduces hepatic epinephrine responsive adenyl cyclase (ERAC) activity. (Glucagon responsive adenyl cyclase is unaffected.) This effect appears to depend on prednisolone mediated increases in serum insulin levels since: 1) Glucagon or insulin (injected for 6–8 days), each reduce ERAC activity in the normal rat; 2) prednisolone or testosterone fails to reduce ERAC activity in the diabetic rat; 3) Diabetes (alloxan or streptozotocin) elevates ERAC activity and insulin reverses the elevation and reduces ERAC activity levels well below those in the normal rat. We suggest that prevailing serum insulin levels regulate hepatic ERAC activity and that this regulation constitutes an additional link between insulin and glucose metabolism (Endocrinology90: 1331, 1972)