A continuous monitoring of mucosal integrity and secretory activity in rat stomach: a preparation using a lucite chamber.

We assembled a new system using a lucite chamber and rat stomach for simultaneous measurement of transmucosal potential difference (PD) and luminal pH as indicators of the mucosal integrity and the secretory activity, respectively. The biological preparation involved only the glandular mucosa and responded to a variety of mucosal damaging agents by different degrees of PD reduction, pH increases and histological damages. When the mucosa was exposed for 10 min to 1 M NaCl, the reduced PD was restored with time, reaching the baseline values within 2 hr with histological restitution. Titration of gastric effluent showed that after the exposure, acid secretion ceased and a considerable amount of HCO3- was evident in the lumen, followed by re-secretion of acid. These secretory changes corresponded with those of luminal pH; this remained elevated for 1 hr after the exposure and returned to the basal values 2 hr later. The histological restitution as well as the PD recovery after damage were significantly interfered with by indomethacin (5 mg/kg, s.c.) or vasopressin (10 unit/kg/hr, i.v.), respectively, at the dose which inhibited the increased pH responses caused by 1 M NaCl or reduced the mucosal blood flow. These results suggest that this system may be useful for studying physiological changes of gastric mucosa after acute injury and for screening drugs that may have an effect on the repair process.