Cardioprotective Effect of Ischemic Preconditioning on Ischemia/Reperfusion Injury in Spontaneously Type 2 Diabetic Rat Hearts (Original)

Objectives and Methods:Although ischemic heart disease is significantly more prevalent and more severe in patients with diabetes mellitus than in the nondiabetic populationexperiments have shown both increased and decreased susceptibility to ischemic injury under different experimental conditions. To clarify the cardioprotective effect of ischemic preconditioning (IP)on ischemia/ reperfusion injury in spontaneously type 2 diabetic ratswe evaluated the duration of ischemia/ reperfusion ventricular tachyarrhythmias(IRVT)using isolated rat hearts. We employed Otsuka Long-Evans Tokushima Fatty(OLETF)rats with obesity and low insulin sensitivity as the model for type 2 diabetes. After 5 minutes of aerobic perfusionthe rats were divided into the following groups:1)control non-IP-treated rats (CIP－)2)control IP-treated rats (CIP＋)3) diabetic non-IP-treated rats (DIP－)4)diabetic IP-treated rats (DIP＋). The IP protocol has three 2minute cycles of ischemia followed by 5 minutes of reperfusion and 10 minutes of sustained ischemia. Results:The duration of IRVT was significantly shorter in CIP＋ (6.7±4.6 minutes)than in CIP－ (17.7±2.0 minutes p＜0.05). There was however the duration of IRVT did not differ significantly between DIP－ (16.5±3.6 minutes) and DIP＋ (13.3±4.6 minutes). The degree of recovery of left ventricular function(left ventricular pressure ＋dp/dt －dp/dtand coronary flow volume)after reperfusion was also significantly greater in CIP＋ than in CIP－. Howeverthe degree of recovery of left ventricular function did not differ significantly between DIP－ and DIP＋. Conclusion:These results suggest that the cardioprotective effects of IP are attenuated in type 2 diabetic model rats. (Jikeikai Med J 2006;53:69-79)