Studies on ethanol-induced subepithelial fluid accumulation and jejunal villus bleb formation. An in vitro video microscopic approach

Abstract

Jejunal intraluminal ethanol causes morphological and mucosal microvascular injury. The purpose of the present study was to understand the mechanism of the morphological alterations caused by ethanol without the influence of ethanol's effect on the microcirculation. Therefore, we have investigated the ethanol-induced morphological changes in the absence of blood flow (i.e., in the jejunum in vitro) and compared these changes with those reported to occur in the presence of microcirculation (i.e., in the jejunum in vivo). The mucosa of jejunal segments was exposed to a control solution and to solutions containing 0.8, 1.6, and 4.8% (w/v) ethanol, using a specially designed apparatus. The morphological response of the mucosa to these solutions was continuously examined employing a video microscopic technique, and the changes were morpho-metrically evaluated on subsequent playback of videotapes. Ethanol caused a concentration-dependent increase in the number of villi with subepithelial fluid accumulation, i.e., blebs, and a decrease in the height of the villus core (i.e., lamina propria). With 0.8 and 1.6% ethanol, the contracted core remained partially attached to the epithelium and the total villus height (villus core plus epithelial layer) decreased. With 4.8% ethanol, the villus core contraction was so rapid that the stroma fully separated from the epithelium. Thus, among other factors, the rapidity of the villus core contractions appears to play a role in the subepithelial bleb formation and in the appearance of the bleb. The ethanol-induced changes in vitro are similar to those reported to occur in the jejunum in vivo. Therefore, we conclude that the effect of ethanol on morphology is independent of its action on the microcirculation.Key words: video microscopy, villus contraction, villus core contraction, bleb formation, jejunal injury.