Reduced mucosal perianastomotic capillary density in rat small intestine with chronic radiation damage

Anastomoses in an intestine with chronic radiation damage are prone to leak age, possibly due to a reduced blood supply induced by a reduced capillary bed. In an animal model, the numerical capillary density in the perianastom otic area was investigated in intestine with or without chronic radiation d amage. A 2-cm segment of rat ileum received a single dose of 21 Gy. Twenty weeks later, when the chronic radiation-induced changes were established, a n anastomosis was constructed in this segment and in a corresponding segmen t in control rats. In situ perfusion fixation of the intestine was done 4 o r 7 days after construction of the anastomosis, sections of the intestine w ere removed surgically, the specimens were embedded in methacrylate plastic and sectioned at 2.5 mu m, and capillaries were counted under a light micr oscope. The circumferential mucosal capillary density was lower in irradiat ed than in nonirradiated animals at both 4 and 7 days (P < 0.001 and P = 0. 04, respectively). This reduction was greater in the mesenteric quadrant th an in the other quadrants around the circumference. These results are indic ative of a reduced capillary bed in the vicinity of anastomoses in intestin e with chronic radiation damage, which might lead to an impeded blood suppl y and subsequent leakage. (C) 1998 by Radiation Research Society.