Aims: Apelin, an endogenous cytokine, has a number of biological effects on the cardiovascular system, including a cardioprotective effect and calcium modulation. Because the intracellular calcium abnormality is considered to play an important role in cardiac dysfunction induced by ischaemia-reperfusion (I/R), the aim of this study was to examine the effects of apelin-13 on I/R-induced changes in cardiac performance and sarcoplasmic reticulum (SR) function.
Methods and results: Isolated rat hearts were subjected to global ischaemia followed by reperfusion in the absence or presence of apelin-13 and inhibitors of some survival kinases. We found that depressed cardiac performance induced by I/R was attenuated by apelin-13. Furthermore, apelin-13 depressed oxidative stress during I/R. SR function depressed during I/R was partly reversed by apelin-13. SR oxidative modification levels were increased in I/R and reversed by apelin. Inhibitors of phosphatidylinositol-3-kinase and protein kinase C abolished the effects of apelin. Apelin-13 maintained the Ca(2+) transient against I/R in cardiomyocytes.
Conclusion: Apelin protects SR function and cardiac performance during I/R by attenuating oxidation of sarco(endo)plasmic reticulum Ca(2+)-ATPase and RyR.
Keywords: Ca2+; Ischaemic contracture; PI3K; PKC; ROS.