Differences in response of psoriatic epidermis in cyclic AMP accumulation against certain adenyl cyclase agonists

Epidermal slices of pig skin and psoriatic human skin were used in a study on responses of adenyl cyclase to epinephrine, histamine and adenosine. In pig skin, histamine stimulated adenyl cyclase slightly more than epinephrine. The histamine concentration eliciting the maximum cyclic AMP accumulation was 5 x 10(-4)M, which was 20 times greater than that of epinephrine. The optimal concentration of adenosine seemed to be an additional 10 times higher (5 x 10(-3)M). When involved and uninvolved epidermal specimens from 18 psoriatic patients were incubated with these three agents, cAMP formation with histamine was unchanged or slightly increased in involved epidermis, while the response to epinephrine was markedly depressed and to adenosine moderately so. These findings suggest further that there is a selective defect in the membrane enzyme system in psoriatic epidermis.