Noninvasive limb ischemic preconditioning protects against myocardial I/R injury in rats.

BACKGROUND: Transient limb ischemia induces remote early preconditioning that protects the myocardium from ischemia/reperfusion (I/R). However, it is unknown whether limb ischemia induces remote late preconditioning and whether it induces the same magnitude of cardioprotection compared with cardial ischemic preconditioning (CIP). We tested the hypothesis that late remote preconditioning of noninvasive limb ischemia (NLIP) offers the same magnitude of cardioprotection against myocardium I/R injury. METHODS: Thirty Wistar rats weighing 240-260 g each were randomly divided into three groups: I/R, CIP, and NLIP. The mean arterial pressure (MAP), heart rate (HR), ST-segment, ventricular arrhythmia, and CK-MB, cTnI, and superoxide dismutase (SOD) activity were measured after 0 and 30 min of ischemia and after 120 min of reperfusion. Myocardial infarct size, histologic examination, MMP-2, MMP-9, and TIMP-1 protein expression were determined at the end of the experiment. RESULTS: Compared with I/R groups, CIP and NLIP reduced ST-segment elevation (P<0.01), decreased incidence and duration of ventricular arrhythmia (P<0.01) during ischemia, decreased CK-MB (P<0.05), and cTnI (P<0.01) activity, and increased SOD (P<0.05) activity after reperfusion. The myocardial infarct size (P<0.01) was significantly reduced, and cell injury was attenuated in the CIP and NLIP groups compared with the I/R group. MMP-2 and MMP-9 protein expression was significantly decreased in the CIP and NLIP groups (P<0.01), while TIMP-1 expression was significantly increased in the CIP and NLIP groups compared with the I/R group (P<0.01). CONCLUSION: Remote preconditioning via NLIP has late cardioprotection against myocardium I/R injury and has a similar magnitude of cardioprotection compared with CIP in rats.