Time-course changes in gastric mucosal blood perfusion following portal vein constriction in rats

Gastric mucosal blood flow is increased in all experimental models of chronic portal hypertension, when portosystemic shunting and the hyperdynamic circulation are fully developed. However, some controversy exists concerning the time course of this event. This study was undertaken to investigate the chronological changes in gastric mucosal blood perfusion during the first 7 days after partial portal vein constriction.

Portal hypertensive and sham operated animals were studied. Gastric mucosal blood flow was measured by hydrogen-gas clearance and gastric oxygen and hemoglobin content by reflectance spectrophotometry, prior to and immediately after partial portal vein constriction, and 1, 2, 7 and 15 days after induction of portal hypertension.

Immediately after partial portal vein constriction, gastric mucosal blood flow and gastric oxygen were significantly decreased by 27% and 32% respectively, and gastric hemoglobin significantly increased by 19%. On day 1, gastric mucosal blood flow was increased in both portal hypertensive and sham operated rats. However, while this parameter returned to normal in sham operated rats, it remained high on days 2, 7 and 15 in portal hypertensive rats. In portal hypertensive rats, gastric oxygen values were not significantly different from those in sham operated animals, but hemoglobin tended to increase with development of portal hypertension, being significantly higher than in sham operated rats at days 2 and 7. Similar results were obtained when analyzing gastric mucosal blood perfusion 2 and 7 days after two-staged total portal vein constriction.

Increased gastric mucosal blood perfusion is present in portal hypertensive rats from the first day after partial portal vein constriction. The lack of significant differences in all parameters on day 1 between portal hypertensive and sham operated rats is probably related to an increased mucosal blood perfusion related to surgery.