Calcium–Secretagogue Interaction in the Stimulation of Gastric Acid Secretion 1

Abstract

Summary

Gastric epithelia were depleted of Ca²⁺ in the continued presence of secre-tagogues by removing this cation from the bathing media and repeated washouts with or without EDTA until acid secretion was reduced to zero. Under these conditions, both the transmucosal PD and resistance declined. Incubation of these epithelia in presence of 1 mM Ca²⁺ in the luminal bathing medium resulted in a partial reversal of PD and resistance with initiation of some secretion, in contrast to near complete reversal obtained following restoration of Ca²⁺ to the serosal bathing medium. Dibutyryl cyclic-AMP or theophylline enhance acid secretion in these circumstances without complete reversal of PD and resistance. These observations suggest that cellular Ca²⁺ may play a direct role in the production of H⁺ per se by mediating the secretagogue effect in raising intracellular cyclic-AMP levels, in addition to its established role in the maintenance of integrity of junctional complexes which are essential for the luminal segregation of H⁺ in the secretory process.