Sequence of morphological and hemodynamic changes of gastric microvessels in portal hypertension

Changes in gastric microvasculature and blood flow at different phases of portal hypertension were studied in rats 1, 2, 3, 4, and 15 days after induction of portal hypertension or sham operation. Vessel lumen and vessel wall thickness were expressed as a ratio referred to the vessel size. On day 2 after constriction of the portal vein, gastric blood flow was decreased (0.57 +/- 0.06 vs. 0.99 +/- 0.20 mL.min-1.100 g-1; P less than 0.05), and gastric vessels had a distended lumen (0.42 +/- 0.02 vs. 0.28 +/- 0.03; P less than 0.01) and a thin wall (2.11 +/- 0.2 vs. 3.82 +/- 0.4; P less than 0.01). On day 4, the gastric blood flow of portal hypertensive animals was increased (1.15 +/- 0.14 vs. 0.71 +/- 0.07 mL.min-1.100 g-1; P less than 0.05), whereas gastric vessels had a reduced lumen (0.27 +/- 0.02 vs. 0.33 +/- 0.02; P less than 0.01) and a thick wall (4.19 +/- 0.52 vs. 3.16 +/- 0.30; P less than 0.05). By day 15, vessels with the largest lumens (0.45 +/- 0.01 vs. 0.29 +/- 0.01; P less than 0.01) and the thinnest walls (1.78 +/- 0.26 vs. 3.58 +/- 0.62; P less than 0.01) were observed in portal hypertensive animals. In conclusion, the gastric vessels of the 15-day portal vein-ligated rat resemble the structural abnormalities described in human portal hypertensive gastropathy.