Effect of prostaglandins on adenylate cyclase activities in membranes from liver and transplantable hepatomas.
The effects of prostaglandins on adenylate cyclase activity have been examined in membranes purified from normal rat liver and from a series of Morris hepatomas. Prostaglandin E1 gave the greatest stimulation (up to two-fold) in all membranes. However, prostaglandins A1, A2, and F2alpha, although stimulatory in liver and four tumor membranes, were inhibitory of adenylate cyclase activity in membranes from two of the fast-growing tumors. Arrhenius plots yielded broken line curves (at 20 degrees C) for the basal activity of all enzymes. Addition of various prostaglandins caused shifts in the broken line curves and/or produced nonbroken (straight) line curves for the liver and many of the hepatoma adenylate cyclases.更多