Beta-adrenergic and prostanoid inhibition of canine fundic mucosal mast cells

Abstract

We examined regulation of histamine release from canine hepatic and fundic mucosal mast cells in short-term culture. We found that beta- but not alpha-adrenergic agonists markedly inhibited concanavalin A (ConA)-stimulated histamine release. Inhibition by epinephrine was reversed by the beta-antagonist propranolol, but not by the alpha-adrenergic antagonists phentolamine or yohimbine. The beta 2-selective antagonist ICI 115881 reversed the effects of epinephrine, whereas the beta 1-antagonists practolol and betaxolol had little effect. Prostaglandin E2 (PGE2), but not its analogue enprostil, inhibited ConA-stimulated histamine release. This difference may relate to the ability of PGE2, but not enprostil, to stimulate adenosine 3',5'-cyclic monophosphate (cAMP) production. Forskolin, cAMP analogues, and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine also effectively inhibited ConA-stimulated histamine release. Neither adrenergic agonists nor PGE2 inhibited histamine release stimulated by the combination of phorbol 12-myristate-13-acetate plus the calcium ionophore A23187. These data suggest that inhibition was mediated via cAMP-dependent mechanisms and was exerted on primary cell activation, rather than on postreceptor activating events.