Ischemia-reperfusion induced gastric mucosal microcirculatory alterations in the rat

The aim of this study was to determine the gastric microcirculatory alterations occurring during reperfusion after a period of ischemia and the possible role of oxyradicals in the microcirculatory disturbance. An in vivo microscopy technique was used to observe the superficial mucosal blood flow during reperfusion. After reperfusion, mucosal blood flow resumed quickly and then slowed with eventual cessation of flow. Thirty minutes of ischemia followed by reperfusion resulted in cessation of flow in 50 +/- 4% and 81 +/- 8%, of the capillaries in the microscopic field at 15 and 30 min, respectively, after reperfusion. During this mucosal microcirculatory change, numerous white thrombi were observed flowing in the mucosal microvessels. In rats pretreated with allopurinol to inhibit oxyradical formation, blood flow was maintained to a significant and markedly greater extent. Study of the submucosal microvasculature after reperfusion revealed a marked delay in transit of a fluorescein-albumin bolus from terminal submucosal arterioles through the mucosal microvasculature and back to submucosal collecting venules. Submucosal vascular diameter change could not explain the altered mucosal blood flow. These findings indicate that there is marked slowing and cessation (in many microvessels) of gastric mucosal blood flow during reperfusion after a period of ischemia, and that the obstruction to flow occurs in the mucosal microvessels. The results of the study with allopurinol suggest that oxygen-derived free radicals generated by xanthine oxidase may play a major role in the genesis of this gastric mucosal microcirculatory disturbance.