Time as a factor in the expression of ethanol injury to the gastric mucosa

A technique of quantitative histology was used to assess the influence of time after injury on the histological expression of gastric mucosal damage. Rats, pretreated with either natural prostaglandin E2 or saline, were subjected to intragastric administration of either 50% or 100% ethanol. Fifteen minutes later the ethanol was removed from the stomach. Rats were sacrificed at either 30 min or 24 h after ethanol instillation. In rats pretreated with saline and subjected to 100% ethanol with or without prostaglandin pretreatment, the extent of deep mucosal damage was markedly underestimated by early evaluation. Only 5.4% of the volume of the gastric mucosa showed evidence of damage at 30 min after ethanol, compared with 57.3% of the volume of the mucosa, at 24 h after 100% ethanol exposure. Assessment of gastric mucosa 24 h after ethanol injury showed that PGE2 reduces the extent of surface area damaged and the volume of the mucosal damage. When 50% ethanol was used as the injurious agent, no difference was noted in the volume of the mucosa damaged when the stomach was assessed at either 30 min or 24 h after injury. These results indicate that full histological expression of injury is not present 30 min after 100% ethanol instillation, at least in part because of fixation of the gastric mucosa by 100% ethanol. Fifty per cent ethanol, which does not cause mucosal fixation, may be better as a test agent.