[Repair of the duodenal mucosa following acid damage. A protective mechanism as an approach to new therapeutic principles?].

Epithelial repair after luminal acid exposure was studied in the rabbit duodenum in vivo, HCl (200 mM for 30 min) caused uniform damage of the mucosa confined to the villi, 50% of the total villus height was affected by the acid-induced lesion in the proximal, and 70% in the distal duodenum. After demarcation and detachment of the necrotic tissue the defect was bridged by the remaining viable epithelial cells underneath a layer of mucus and necrotic debris (= necrotic layer). Mucosal repair resulted in a reduction of villus height by 62% in the proximal, and 77% in the distal duodenum. This process of mucosal repair progressed continuously, so that 9 hours after acid damage only 33% of villi in the proximal, and 41% in the distal duodenum were not yet fully restored, irrespective of luminal pH(pHL = 7 or pHL = 3). The difference between proximal and distal duodenum is due to the higher acid susceptibility of the distal duodenum. Rapid epithelial repair of the duodenal mucosa in vivo provides an important protective mechanism against the aggression from luminal acid.