Effect of the Ligation and Reperfusion Timeframe on Maximal Ischemia-Reperfusion Injury in Diverse Rat Models

Background: Little is known about the effect that different time sequences for coronary ligation and reperfusion have on ischemic-reperfusion (IR) injury. Objective: To investigate the relationship between the extent of IR injury and the timeframe for coronary ligation/ reperfusion in three animal models. Methods: Three rat models were used: normal Sprague-Dawley rats, diabetes mellitus (DM) rats, and fat rats. The rats in each model were divided into four groups based on the coronary ligation period (L): 30, 60, 120, and 180 min, and then divided into seven sub-groups based on the reperfusion period (R): 0, 30, 60, 120, 180, 270, and 360 min. R0 was the IR injury baseline for each sub-group. The hearts were harvested and stained with Evans blue and 2,3,5-triphenyl tetrazolium chloride dye to distinguish the different myocardial injury areas: area at risk (AAR) and myocardial necrosis. The difference between each subgroup and baseline (R0) for the necrotic area/AAR was calculated. Results: In the normal rats, the highest IR injury differences compared with the baseline group occurred at L120, with a reperfusion time of > 180 min. The highest IR injury difference compared to the baseline group occurred at L30, with a reperfusion time of > 180 min in the DM rats and at L60R270, L120R180 in the fat rats. Conclusions: IR injury, as induced by different coronary ligation and reperfusion time intervals, had diverse expression profiles in the different animal models. Optimal animal models with optimal coronary ligation/reperfusion protocols to achieve maximal IR injury will affect the results and interpretation of future studies.