RNAi targeting ryanodine receptor 2 protects rat cardiomyocytes from injury caused by simulated ischemia-reperfusion.

The effects of a small interfering RNA targeting ryanodine receptor 2 (si-Ryr2) on cardiomyocytes injury following a simulated ischemia-reperfusion (I/R) were investigated. Pretreated with si-Ryr2 or ryanodine, primary cultures of neonatal rat cardiomyocytes were subjected to a protocol of simulated I/R. Compared with control, the cytosolic Ca(2+) concentration ([Ca(2+)](i)) and the generation of reactive oxygen species (ROS) was significantly augmented after I/R. Concomitant with these, cell injury assessed by Annexin V/PI staing, mitochondria membrane potential (DeltaPsim) and the leakage of lactic dehydrogenase (LDH) and creatine phosphokinase (CPK) were aggravated. Si-Ryr2 treatment reduced [Ca(2+)](i) and ROS generation and protected the cardiomyocytes from subsequent I/R injury, as evidenced by stable DeltaPsim and decreased Annexin V(+) PI(-) staing and enzymes release. Moreover, si-Ryr2 exerted more effective protection on I/R injury compared to ryanodine. The present study demonstrated for the first time that in neonatal cardiomyocytes, si-Ryr2 reduces cell death associated with attenuating [Ca(2+)](i) and ROS production. Furthermore, we attempt to speculate that si-Ryr2 excel ryanodine in Ryr2 function research of cardioprotection.