Cyclic AMP increase by histamine and its analogues in guinea-pig submandibular gland

The effect of histamine and its analogues on the cyclic AMP level in chopped guinea-pig submandibular glands was investigated. These agonists increased the cyclic AMP level dose-dependently. The ED50 values for histamine and 4-methylhistamine were approximately 1.3 x 10(-5) M and 2.2 x 10(-5) M, respectively. The efficacy of 4-methylhistamine was higher than that of histamine. 2-(2-Pyridyl)-ethylamine was far less effective compared with histamine or 4-methylhistamine. Metiamide markedly antagonized the cyclic AMP response to histamine and 4-methylhistamine, but mepyramine was ineffective. A combination of aminoguanidine and quinacrine had no influence on the effect of histamine on the cyclic AMP level. These results indicate the H2-type histamine receptors which mediate the cyclic AMP increase are present in the guinea-pig submandibular gland.