Effect of amino acids on H+ production by isolated rat parietal cells

We investigated the hypothesis of a direct effect of amino acids on gastric parietal cells. [14C]aminopyrine uptake into isolated enriched rat parietal cells served as a quantitative index of H+ production. Cells were incubated in media containing 1 mM Ca2+ in the absence or presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), or 3 mM Ca2+ without IBMX. Under these different conditions, L-arginine, L-phenylalanine and L-tryptophan (10(-6) M to 3 X 10(-2) M) failed to alter basal [14C]aminopyrine uptake as well as the response to submaximal stimulation by histamine, forskolin, N6O2-dibutyryladenosine-3',5'-(cyclic)-phosphate (db cAMP) or carbachol. Pentagastrin failed to elicit an appreciable response in the presence and absence of 10(-3) M of all three amino acids studied. It is concluded that in vivo the potent stimulation of gastric acid secretion by L-arginine, L-phenylalanine and L-tryptophan is mediated by other than direct mechanisms.