Portal hypertension and gastric mucosal injury in rats. Effects of alcohol.

The present study was performed primarily in order to determine whether gastric mucosa of rats with portal hypertension has different functional and histologic features when compared with controls, and second to quantitate and compare morphologic and functional changes after exposure to topical ethanol. Portal hypertension was produced by staged portal venous occlusion, and in these animals portal pressure was 32 +/- 2 cm saline compared with 18 +/- 2 cm in sham-operated controls (p less than 0.005). Before ethanol, portal hypertensive rats compared with controls had significantly higher luminal pH (2.9 +/- 0.3 vs. 1.9 +/- 0.1), increased H+ back-diffusion (loss of 138 +/- 10 vs. 57 +/- 16 microEq H+/h), lower potential difference (8 +/- 1 mV lower than controls), and extensive submucosal edema (submucosal thickness 325 +/- 25 vs. 138 +/- 18 micrometers). After 3 h of exposure to 2 ml intragastric absolute ethanol, the area of macroscopic hemorrhagic mucosal injury was significantly greater in portal hypertensive rats than in controls (34.0 +/- 8.7% vs. 7.6 +/- 2.1%), confirmed histologically by the greater number of deep hemorrhagic necrotic lesions and extent of mucosal length involved. Furthermore, after ethanol, portal hypertensive rats compared with controls had significantly increased gastric volume (14.4 +/- 1.5 vs. 8.3 +/- 0.6 ml), Na+ (86.6 +/- 8.0 vs. 64.6 +/- 8.0 mEq/L), pH (7.1 +/- 0.3 vs. 4.3 +/- 0.4), H+ back-diffusion (loss of 309 +/- 41 vs. 207 +/- 33 microEq H+/h), and protein and blood loss (100% increases over controls). These results indicate that gastric mucosa of portal hypertensive rats has distinctive functional and histologic abnormalities that can explain its increased susceptibility to erosive injury after ethanol. This study quantitatively confirms in an animal model the clinical observations that portal hypertension may predispose to severe gastric mucosal injury.