Changes in the Microvasculature of Small Bowel Mesentery in Rats with Prehepatic Portal Hypertension: the Preliminary Study in vivo

Abstract

According to the literature, neoangiogenesis in the mesentery of the small intestine is the trigger of portosystemic collateral circulation in portal hypertension. However, the types of blood vessels involved in this process have not been established. The aim of this study was to determine which type of the mesenteric microvessels participates in angiogenesis in portal hypertension. Studies were performed in 12 adult outbred female rats weighing 250 ± 50 g which were divided into two groups: sham-operated (n = 5) and experimental (n = 7). The mesenteric microcirculation of rats in both groups was examined by intravital microscopy during the first laparotomy and relaparotomy on the 15th day of the experiment. In contrast to the sham-operated animals, prehepatic portal hypertension was induced in rats of the experimental group by partial portal vein ligation during the first operation. Portal pressure was measured in both groups at the time of the second operation. The portal pressure in rats of the experimental group was significantly higher than in sham-operated rats: 12,53 ± 1,26 mm Hg and 9,34 ± 0,14 mm Hg, respectively (p<0,01). There was a significant increase in the number of capillaries (p <0,05) and total vascular density (p <0,05) in rats of both groups by the 15th day of the experiment. At the same time, a greater increase in the capillary network was observed in rats of the experimental group (p <0,05), whereas no significant differences were found in the values of vascular density of the other types of blood vessels. Changes in the mesenteric microvasculature in portal hypertension lay in the increase in the values of vascular density, which occurred mostly at the expense of capillaries.