Direct effect of ethanol on acid secretion in isolated canine gastric mucosa

The direct effects of ethanol on resting and secreting (histamine = H, pentagastrin = G, and acetylcholine = A) gastric mucosa were determined using an in vitro chamber preparation. Ethanol (E) produced no effect on acid (H+) secretion during resting conditions but concentrations above 2% (4% and 8%) decreased electrical potential difference (PD), short-circuit current (Isc) and resistance (R). With H-induced H+ secretion, E at 8% on mucosal side decreased H+ secretion (4.11 +/- 0.34 to 0.64 +/- 0.45 microEq/cm2hr), Pd (32 +/- 2 to 4.9 +/- 0.6 mV), Isc (5.0 +/- 0.3 to 1.1 +/- 0.1 microEq/cm2hr), and R (237 +/- 15 to 174 +/- 68 hm . cm2). Washout of E produced recovery in all parameters. With P-induced H+ secretion, E decreased H+ secretion (1.63 +/- 0.11 to 0.51 +/- 0.18), PD (42 +/- 5 to 13 +/- 3), Isc (5.71 +/- 0.38 to 2.22 +/- 0.45), and R (274 +/- 21 to 218 +/- 13). With A-induced H+ secretion, E decreased H+ secretion (1.16 +/- 0.06 to 0.45 +/- 0.23), PD (38 +/- 1 to 12 +/- 1), Isc (5.69 +/- 0.40 to 1.94 +/- 0.09) and R (253 +/- 22 to 226 +/- 22). When E was placed on the serosal side, 10% was necessary to inhibit H+ secretion and all the electrical parameters increased. Hypertonic sucrose (695.6 mM in mucosal side) produced an immediate decrease in H+ secretion, PD and Isc but increased R. These data indicate that the direct action of E is not to stimulate but rather to inhibit secretagogue-induced gastric H+ secretion.