Hypoxic preconditioning protects rat hearts against ischemia–reperfusion injury via the arachidonate12-lipoxygenase/transient receptor potential vanilloid 1 pathway
pmid: 24816396
Hypoxic preconditioning protects rat hearts against ischemia–reperfusion injury via the arachidonate12-lipoxygenase/transient receptor potential vanilloid 1 pathway
Hypoxic preconditioning (HPC) protects rat hearts against ischemia-reperfusion (IR) injury. However, the role of transient receptor potential vanilloid 1 (TRPV1) in HPC-mediated cardioprotection remains unknown. TRPV1 is activated by endovanilloid 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], which is synthesized by arachidonate 12-lipoxygenase (ALOX12). Therefore, we examined whether HPC protects the myocardium against IR via the ALOX12/TRPV1 pathway. Compared to hearts of rats kept in room air, the hearts of rats kept in air with 10 % oxygen for 4 weeks had better post-ischemic recovery and less tissue damage when subjected to 30-min global ischemia and 4-h reflow in a Langendorff apparatus. Capsazepine, a specific TRPV1 blocker, administered 5 min before reperfusion markedly attenuated the effects of HPC, confirming that TRPV1 is a downstream effector in HPC-mediated cardioprotection. HPC resulted in the upregulation of ALOX12 and myocardial 12(S)-HETE, and prevented IR-induced 12(S)-HETE reduction. In addition, sarcolemmal ALOX12 expression in HPC hearts mainly co-localized with TRPV1 expression. Blockade of ALOX12 by cinnamyl-3,4-dihydroxy-α-cyanocinnamate or baicalein abrogated the effects of HPC, baicalein also decreased 12(S)-HETE expression. Mimicking HPC by given 12(S)-HETE or capsaicin to baicalien-treated hearts enhanced cardiac recovery during reperfusion. The cardiac protein kinase C (PKC) isoforms α, δ, ε, and ζ were preferentially expressed in the sarcolemmal membrane of HPC-treated hearts, indicating their high intrinsic activation state. Capsazepine or co-treatment with baicalein attenuated translocation of PKCα, PKCδ and PKCε, but not that of PKCζ. We conclude that HPC reduces heart susceptibly to IR via ALOX12/TRPV1/PKC pathway, as shown by increased 12(S)-HETE expression in HPC hearts.
- Memorial Hospital of South Bend United States
- National Cheng Kung University Taiwan
- Fu Jen Catholic University Taiwan
- National Taiwan University of Arts Taiwan
- National Taiwan University Hospital Taiwan
Male, Time Factors, TRPV Cation Channels, Myocardial Reperfusion Injury, In Vitro Techniques, Arachidonate 12-Lipoxygenase, Caffeic Acids, Sarcolemma, Animals, 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid, Lipoxygenase Inhibitors, Rats, Wistar, Hypoxia, Protein Kinase C, Myocardium, Isoenzymes, Protein Transport, Flavanones, Capsaicin, Signal Transduction
Male, Time Factors, TRPV Cation Channels, Myocardial Reperfusion Injury, In Vitro Techniques, Arachidonate 12-Lipoxygenase, Caffeic Acids, Sarcolemma, Animals, 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid, Lipoxygenase Inhibitors, Rats, Wistar, Hypoxia, Protein Kinase C, Myocardium, Isoenzymes, Protein Transport, Flavanones, Capsaicin, Signal Transduction
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