On the mechanism of tachyphylaxis to histamine in guinea pig seminal vesicle.

Repeated administration of high concentrations (10 muglml and above) of histamine produce tachyphylaxis in the seminal vesicle of guinea pig. Acetylcholine partially restores the response to histamine after development of constant tachyphylactic response. No tachyphylaxis occurred (in few experiments) in which the preparation is atropinized. Prior eserinization potentiates the response to histamine. After development of tachyphylaxis to histamine, increasing doses of histamine fail to produce log dose increase in the response. The results suggest that tachyphylaxis to histamine involves, desensitization of the receptors and further, a decrease in the release of acetylcholine may also contribute to the development of tachyphylaxis.