Effects of ethanol on adenylyl cyclase in platelets and in HEL cells

Abstract

Background: The cAMP signal transduction systems are known to play a critical role in the acute and chronic effects of ethanol and other drugs of abuse. Objective: To investigate the role of protein kinase C (PKC) in the action of ethanol on platelets and human erythroleukemia (HEL) cells. Methods: HEL, HEK 293 cells [transfected with AC type VII(AC7)] and platelets were used to study the effects of ethanol. cAMP accumulation assay was used to determine the percentage conversion of [3H]ATP into [3H]cAMP. Each fraction was separated through sequential chromatography and the radioactive material was then quantified using a liquid scintillation counter. Results: Ethanol enhanced the PGE1-stimulated AC activity in HEL cells. The percent enhancement of cAMP accumulation by 200 mM ethanol was similar in HEL cells, platelets and HEK 293 cells transfected with AC7. When combined with PDBu, 200 mM ethanol further enhanced the PDBu stimulation of AC activity suggesting a separate mechanism by which ethanol and PDBu exert their effects on the AC. Pretreatment of the cells with staurosporine and chelerythrine significantly blocked the PDBu-and/or ethanol-enhancement of cAMP accumulation. Conclusion: These results indicate a clear role for PKC in the action of ethanol on AC in platelets.