Abstract
Prostaglandin E2 (PGE2) differentially inhibited histamine and isoproterenol stimulation of [14C]aminopyrine accumulation in rat parietal cell preparations. Low concentrations of PGE2 decreased the maximum response to isoproterenol whereas higher concentrations increased the EC50 of histamine with only a modest effect on the maximum response. Also, PGE2 potentiated dibutyryl cyclic AMP stimulation of aminopyrine accumulation in either the absence or presence of carbachol. In contrast, PGE2 inhibited potentiation between carbachol and histamine due to its inhibitory effect on histamine and possibly also to an inhibitory effect on cholinergic activity. Islet activating protein prevented the inhibitory actions of PGE2. To account for these results a model is presented based on the recent proposal by Gilman (Cell 36: 577-579, 1984) of an interaction between components of adenylyl cyclase stimulatory and inhibitory guanine nucleotide binding proteins.
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