ADAPTIVE CYTOPROTECTION AGAINST ETHANOL-INDUCED SMALL-INTESTINAL MUCOSAL INJURY

Exposure of the small intestinal mucosa to 6% ethanol (which is found in human jejunum during alcohol consumption) causes morphological alte rations, and increased permeability of the mucosa and histamine releas e from intestinal mast cells. The released histamine is shown to media te a significant component of the increased mucosal permeability (i.e. , mucosal injury). In the present study, we have investigated whether adaptive cytoprotection occurs against the increased mucosal permeabil ity and histamine release induced by 6% ethanol. Rabbits were used. In each animal, three adjacent segments of upper small intestine were pr e-perfused for 30 min, and then perfused for 90 min in the following o rder: control solution followed by control solution (control segment); control solution followed by 6% ethanol (ethanol segment); 1% ethanol followed by 6% ethanol (pretreated ethanol segment). During the 90-mi n perfusion, mucosal permeability of each segment was measured by anal yzing the effluent for intraluminal clearance of i.v. administered Cr- 51-labelled ethylenediaminetetraacetic acid (Cr-51-EDTA) and I-125-lab elled bovine serum albumin (I-125-BSA). Mast cell histamine release wa s assessed by determining histamine concentration of the gut effluent. All measurements were higher in the ethanol segments than in the cont rols. These ethanol effects were significantly lower in the pretreated ethanol segments, indicating that adaptive cytoprotection occurs agai nst the mucosal injury induced by 6% ethanol. These findings are discu ssed in relation to the literature on mucosal effects of intestinal in traluminal ethanol.