Adenylate cyclase and cyclic AMP-phosphodiesterase activities of fetal membranes: effect of insulin.

Basal activity and response to insulin of adenylate cyclase and cyclic AMP-phosphodiesterase were measured in the fetal membranes before and after labor. Basal activity of adenylate cyclase showed only slight variations after delivery when compared to that observed before labor. Enzyme activity was significantly although weakly decreased by insulin both in the amnion and in chorion before labor, while after delivery a weaker non-significant inhibition was observed. Basal activity of cyclic AMP-phosphodiesterase was lower after delivery with respect to that observed before labor. Insulin inhibited enzyme activity in all conditions. Cyclic AMP levels in intact tissue were not substantially modified by insulin.