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Angiotensin II‐preconditioning is associated with increased PKCε/PKCδ ratio and prosurvival kinases in mitochondria

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Clinical and Experimental Pharmacology and Physiology

Published online on


Angiotensin II‐preconditioning (APC) has been shown to reproduce the cardioprotective effects of ischaemic preconditioning (IPC), however, the molecular mechanisms mediating the effects of APC remain unknown. In this study, Langendorff‐perfused rat hearts were subjected to IPC, APC or both (IPC/APC) followed by ischaemia‐reperfusion (IR), to determine translocation of PKCε, PKCδ, Akt, Erk1/2, JNK, p38 MAPK and GSK‐3β to mitochondria as an indicator of activation of the protein kinases. In agreement with previous observations, IPC, APC and IPC/APC increased the recovery of left ventricular developed pressure (LVDP), reduced infarct size (IS) and lactate dehydrogenase (LDH) release, compared to controls. These effects were associated with increased mitochondrial PKCε/PKCδ ratio, Akt, Erk1/2, JNK, and inhibition of permeability transition pore (mPTP) opening. Chelerythrine, a pan‐PKC inhibitor, abolished the enhancements of PKCε but increased PKCδ expression, and inhibited Akt, Erk1/2, and JNK protein levels. The drug had no effect on the APC‐ and IPC/APC‐induced cardioprotection as previously reported, but enhanced the post‐ischaemic LVDP in controls. Losartan, an angiotensin II type 1 receptor (AT1‐R) blocker, abolished the APC‐stimulated increase of LVDP and reduced PKCε, Akt, Erk1/2, JNK, and p38. Both drugs reduced ischaemic contracture and LDH release, and abolished the inhibition of mPTP by the preconditioning. Chelerythrine also prevented the reduction of IS by APC and IPC/APC. These results suggest that the cardioprotection induced by APC and IPC/APC involves an AT1‐R‐dependent translocation of PKCε and survival kinases to the mitochondria leading to mPTP inhibition. In chelerythrine‐treated hearts, however, alternate mechanisms appear to maintain cardiac function.