Introduction: We aimed to evaluate the impact of gradual blood reperfusion on ischemia/reperfusion injury and to explain the pathophysiology of reperfusion injury in a rat cremaster muscle microcirculation model.

Materials and Methods: 24 Sprague-Dawley rats weighing between 150-200 grams were evaluated in 3 groups. Cremaster muscles were prepared for microcirculatory observations.

Group I (n=8, Control): No ischemia was induced.

Group II (n=8, Acute Reperfusion): Microclamps were applied to the right external iliac vessels for 150 minutes, then venous and arterial clamps ere released at once.

Group III (n=8, Gradual Reperfusion): Microclamps were applied to the right external iliac vessels for 150 minutes, and thereafter first venous clamp was released. Arterial clamp was opened gradually by a specially designed microclamp holder (Sheey ossicle holding clamp). In all groups, following a while of 150 minutes blood flow velocity was measured for 15 minutes and thereafter the animals were reperfused freely for one hour. Next, red blood cell velocity, vessel diameters, functional capillary perfusion, and endothelial edema index; rolling, migrating and adhesing leukocytes and lymphocytes were counted. All observations were videotaped for slow-motion-replay. Muscle damage was evaluated histologically.

Results: In the acute clamp release group, blood velocities increased up to 600% of their preischemic values during postischemic reperfusion period. The numbers of rolling, adhering, and transmigrating leukocytes were significantly higher and histological evaluation revealed more tissue damage in the acute reperfusion group.

Conclusion: Depending on histological and microcirculatory findings, gradual reperfusion was confirmed to reduce the intensity of reperfusion injury.