Effects of CaMKII phosphorylation on myocardial ischemia-reperfusion injury in rats / 中华急诊医学杂志

ABSTRACT

Objective:To explore the effects of calcium/calmodulin dependent protein kinase II (CaMKII) on myocardial ischemia-reperfusion injury in vitro, and apoptosis and autophagy of myocardial cells in isolated rats.Methods:Seventy female SD rats (250-280 g) with normal electrocardiogram were selected to establish the myocardial IR injury model by Langendorff perfusion system. These SD rats were randomly divided into five groups (n=14) cardiac ischemia reperfusion group (IR group), CaMKII phosphorylation activator group (IR+ isoproterenol group), CaMKII phosphorylation inhibitor analogue group (IR+KN92 group), CaMKII phosphorylation inhibitor group (IR+KN93 group), and control group. After reperfusion, the left ventricular function and myocardial morphology were measured to assess the myocardial injury, and TUNEL was performed to assess the apoptosis index. Western blot was used to determine the phosphorylation levels of CaMKII and PLN (p-CaMKII/CaMKII and p-PLN/PLN), and the expression levels of apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3, and autophagy marker proteins LC3II/LC3I, Beclin-1 and P62.Results:Compared with the control group, the left ventricular function of the IR group was decreased, morphological arrangement of myocardial fibers was disordered, and the apoptosis index was increased. The levels of p-CaMKII/CaMKII, p-PLN/PLN, cleaved caspase-3, Bax/Bcl-2, LC3II/LC3I, and Beclin-1 were increased significantly, while the level of P62 was decreased significantly, and apoptosis and autophagy were increased significantly (all P<0.05). Compared with the IR group, the myocardial damage of rats in the IR+KN93 group was significantly improved, the apoptosis index was decreased, and the expression of p-CaMKII/CaMKII, p-PLN/PLN, Cleaved Caspase-3, Bax/Bcl-2, LC3II/LC3I and Beclin-1 were significantly decreased and the level of p62 was remarkable increased, and apoptosis and autophagy decreased significantly (all P< 0.05). Compared with the IR group, the left ventricular function was further decreased in the IR+ isoproterenol group, while the levels of apoptosis and autophagy were further increased ( P < 0.05), while there was no significant difference in myocardial indexes between the IR+ KN92 group and the IR group ( P > 0.05). Conclusions:Inhibition of CaMKII phosphorylation attenuates isolated myocardial ischemia-reperfusion injury by reducing apoptosis and autophagy.