Activation of protein kinase in the guinea pig fundic gastric mucosa by histamine.

The effect of histamine, 1,4-methylhistamine and ethanol on cyclic AMP levels and protein kinase activation was measured in tissue strips from the fundic region of guinea pig gastric mucosa. Histamine induced a significant elevation of tissue cyclic AMP levels and also $\text{in situ}$ activation of the protein kinase. 1,4-methylhistamine, an inactive analog of histamine, and ethanol had no effect on these two parameters. Results suggest that protein kinase activation is involved in the cyclic AMP-mediated action of histamine on the gastric fundic mucosa.