NEUROHORMONAL REGULATION OF HISTAMINE SYNTHESIS IN ISOLATED RABBIT FUNDIC MUCOSAL CELLS

Abstract

In a population of rabbit fundic mucosal cells enriched in mucous and endocrine cells, gastrin and cholecystokinin octapeptide (CCK-8) were shown to increase dose-dependently histidine decarboxylase (HDC) activity with the same efficacy and high potencies [50% effective concentration (EC50) 0.389 +/- 0.041 and 0.275 +/- 0.011 nM, respectively], whereas pentagastrin was less potent (EC50 2.90 +/- 0.13 nM). L-365,260 and PD-135,666 inhibited gastrin- and CCK-8-stimulated HDC activity with a high potency [50% inhibitory concentration (IC50) 1.00 +/- 0.08 and 4.2 +/- 0.7 nM for gastrin-stimulated and 1.95 +/- 0.21 and 1.78 +/- 0.12 nM for CCK-8-stimulated HDC activity, respectively], whereas L-3..