Effects of ethanol on the cyclic AMP system of the dog gastric mucosa.

The effect of ethanol on the cyclic AMP system of the dog fundic mucosa was studied in vitro. The gastric mucosal content of cyclic AMP was increased by 2.5% ethanol, whereas 10 and 20% ethanol decreased the mucosal content of cyclic AMP. The activity of adenylate cyclase was increased by 2.5 and 5% ethanol, whereas 10% ethanol did not significantly affect it. The activity of cyclic AMP phosphodiesterase was inhibited by ethanol in a competitive manner. The increase in the gastric mucosal content of cyclic AMP, induced by low concentrations of ethanol, is apparently due to the stimulation of adenylate cyclase and inhibition of phosphodiesterase. Changes in the phosphodiesterase or adenylate cyclase activites do not explain the decrease of the mucosal content of cyclic AMP by higher concentrations of ethanol. The mechanism of the decrease is discussed.