Ischemia/reperfusion injury in rat mesenteric venules: red blood cell velocity and leukocyte rolling.

The authors determined the effects of 15 (n = 9) and 30 (n = 12) minutes of warm ischemia on the rat mesentery and compared the results with those of a sham-operated group (n = 10). Red blood cell velocity and number of rolling leukocytes were assessed before ischemia as well as 10, 20, 30, 60, 90, and 120 minutes after the start of reperfusion. Leukocyte rolling is considered to be an early step of the inflammatory process. Leukocytes roll along the vessel wall at a velocity that is clearly lower than that of the other blood cells. The preischemic values of red blood cell velocity and number of rolling leukocytes in the 15- and 30-minute ischemia groups did not differ from those of the sham group. In the sham group, no significant changes in red blood cell velocity and number of rolling leukocytes were observed over time. Compared with the sham group, the red blood cell velocity of the 15-minute ischemia group was significantly lower at 30, 60, 90, and 120 minutes after the start of reperfusion the number of rolling leukocytes did not differ significantly. For the 30-minute ischemia group, red blood cell velocity also was significantly lower at 20, 30, 60, 90, and 120 minutes after the start of reperfusion, and the number of rolling leukocytes was higher at 10, 20, and 30 minutes after the start of reperfusion. The results of this study indicate that short periods of total warm ischemia of the rat small bowel and subsequent reperfusion result in a significantly impaired microcirculatory blood flow in the mesentery. However, a prolonged period of ischemia is required to increase leukocyte-vessel wall interactions. In the future, this model will enable us to study the effect of pharmacological interventions during an early stage of the inflammatory response to ischemia/reperfusion in the gut.