Hypoxic preconditioning protects rat hearts against ischemia-reperfusion injury via the arachidonate12-lipoxygenase/transient receptor potential vanilloid 1 pathway

Basic Res Cardiol. 2014 Jul;109(4):414. doi: 10.1007/s00395-014-0414-0. Epub 2014 May 11.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / metabolism
  • Animals
  • Arachidonate 12-Lipoxygenase / metabolism*
  • Caffeic Acids / pharmacology
  • Capsaicin / analogs & derivatives
  • Capsaicin / pharmacology
  • Flavanones / pharmacology
  • Hypoxia / enzymology*
  • In Vitro Techniques
  • Isoenzymes
  • Lipoxygenase Inhibitors / pharmacology
  • Male
  • Myocardial Reperfusion Injury / enzymology
  • Myocardial Reperfusion Injury / prevention & control*
  • Myocardium / enzymology*
  • Protein Kinase C / metabolism
  • Protein Transport
  • Rats, Wistar
  • Sarcolemma / enzymology
  • Signal Transduction* / drug effects
  • TRPV Cation Channels / antagonists & inhibitors
  • TRPV Cation Channels / metabolism*
  • Time Factors

Substances

  • Caffeic Acids
  • Flavanones
  • Isoenzymes
  • Lipoxygenase Inhibitors
  • TRPV Cation Channels
  • Trpv1 protein, rat
  • cinnamyl-3,4-dihydroxycyanocinnamate
  • baicalein
  • 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid
  • Arachidonate 12-Lipoxygenase
  • Protein Kinase C
  • capsazepine
  • Capsaicin