Effects of portal vein stenosis and superior mesenteric vein ligation on mesenteric venous pressure and porta-systemic shunting in the rat
Inflammatory Bowel Diseases
We studied the relative contributions of splanchnic congestion and porta-systemic shunting to the maintenance of experimental portal venous hypertension. Three groups of rats were prepared: portal vein-stenosed, superior mesenteric vein-ligated and sham operated. Though elevated in both operated groups compared to controls, mesenteric venous pressure was highest in the portal vein-stenosed animals (PV vs SMV vs Sham: 19.6 +/- 1.3 vs 15.6 +/- 0.7 vs 13 +/- 0.6; p < .05 PV and SMV vs Sham, and PV vs SMV) despite the presence of 50% porta-systemic shunting in the portal vein-stenosed animals. Shunting was negligible in the other two groups. Peripheral plasma glucagon and vasoactive intestinal peptide (VIP) levels were similar in all three groups. We conclude that mesenteric congestion alone plays a minor role in the pathogenesis of portal hypertension, which may instead be related to the porta-systemic shunting of vasoactive substances other than glucagon and VIP.