Chick retinal pigment epithelium. A new culture system for studying H2-histamine receptors

Histamine elevates the intracellular cyclic AMP levels in cultured embryonic chick retinal pigment epithelium. The half-maximal activity is 6 X 10(-6) M. The effect of histamine is mediated by H2 receptors, i.e., inhibited by the H2 antagonist cimetidine and not affected by the H1 antagonists diphenhydramine and pyrilamine. The inhibition constant (KI) of cimetidine is 1.3 X 10(-8) M. Thus, the present system offers the opportunity of studying the nature of coupling between histamine receptors and adenylate cyclase under controlled conditions in a homogeneous cell type.