CardiothoracicThe Optimal Strategy of Noninvasive Limb Ischemic Preconditioning for Protecting Heart Against Ischemia-Reperfusion Injury in Rats

BackgroundLimb ischemic preconditioning (LIPC) induced by prior brief periods of ischemia-reperfusion (I/R) to a limb is a simple and convenient strategy to protect the heart from I/R injury. However, the optimal strategy is unknown. Therefore, the present study was conducted to test the most effective method of LIPC for clinical applications.MethodsMale Wistar rats were randomized into the following groups: control groups, consecutive LIPC groups, intermittent LIPC groups. The control groups, including the sham operation group, the ischemia-reperfusion (I/R)-control group, the myocardial ischemic preconditioning (MIPC) group, the femoral artery ischemic preconditioning (FAIP) group; the consecutive LIPC groups, including continuously using for 1 d, 3 d, and 7 d groups. Each group was tested on the first, third, and fifth d after LIPC; intermittent LIPC groups, including 1-d LIPC + 1-d interval group, 1-d LIPC + 2-d interval group, 3-d LIPC + 3-d interval group, 3-d LIPC + 5-d interval group. Left ventricular function, incidence of ventricular arrhythmia, and ST-segment were measured during I/R. Myocardial infarct size, creatine kinase isoenzyme MB (CK-MB), and cardiac troponins I (cTnI) were determined at the end of experiment.ResultsCompared with the I/R-controls, the MIPC, FAIP, continuous LIPC for 3 and 7 d and 1-d LIPC + 1-d interval groups showed amelioration of ventricular arrhythmia, improved left ventricular function, lower ST-segment elevation, reduced myocardial infarct size, decreased CK-MB, and cTnI activity. The protective effects of LIPC persisted for 72 h.ConclusionsOur results suggest that a 1-d LIPC + 1-d interval provides optimal cardioprotection from I/R.