Study on tolerance to ischemia-reperfusion injury and protection of ischemic preconditioning of type 1 diabetes rat heart

This study is to investigate changes of tolerance to ischemia-reperfusion (IR) injury and protection of ischemic preconditioning (IPC) of type 1 diabetes rat heart. Type 1 diabetes rat model was made by single injection of streptozotocin and divided into 4 wk (D-4w) group and 8wk (D-8w) group randomly. The two groups were further assigned to six teams: D-4w-con, D-4w-IR, D-4w-IPC, D-8w-con, D-8w-IR and D-8w-IPC team. Normal rats were correspondingly divided into N-4w-con, N-4w-IR, N-4w-IPC, N-8w-con, N-8w-IR and N-8w-IPC team. Heart function, myocardial infarct size, release of lactate dehydrogenase (LDH) and creatine kinase (CK) were detected. And injury increment rate, injury rate and protection rate were calculated. Ultrastructure of cardiomyocyte was observed by electron microscope. The myocardial injury increment rate, infarct sizes in D-con group were all significantly higher than those in N-con rat group, and the degree of injury in D-8w rat hearts was exacerbated compared to D-4w rat hearts. The myocardial injury rate and the injury of cardiomyocyte ultrastructure in D-4w-IR team were lower compared with N-4w-IR group. Compared with D-4w-IR team, IPC decreased infarct sizes in D-4w-IPC group, but its protection rate was lower than that in N-4w-IPC team. Infarct sizes in D-8w-IPC team had no significance with those in D-8w-IR team. The fundament cardiac function of type 1 diabetes rat heart was weakened. Diabetes self could induce heart injury, which could aggravate along with time. The tolerance of 4w type 1 diabetes rat to IR injury is stronger but the protection of IPC was weaker compared to normal rat. The protection of IPC disappears in D-8w group.