Role of PI3Kα and sarcolemmal ATP-sensitive potassium channels in epoxyeicosatrienoic acid mediated cardioprotection

J Mol Cell Cardiol. 2012 Jul;53(1):43-52. doi: 10.1016/j.yjmcc.2012.04.008. Epub 2012 Apr 27.


Aims: Epoxyeicosatrienoic acids (EETs) are cytochrome P450 epoxygenase metabolites of arachidonic acid that have known cardioprotective properties. While the mechanism(s) remains unknown, evidence suggests that phosphoinositide 3-kinase (PI3K) and sarcolemmal ATP-sensitive potassium channels (pmK(ATP)) are important. However the role of specific PI3K isoforms and corresponding intracellular mechanisms remains unknown.

Methods and results: To study this, mice hearts were perfused in Langendorff mode for 40 min of baseline and subjected to 20 or 30 min of global no-flow ischemia followed by 40 min of reperfusion. C57BL6 mice perfused with 11,12-EET (1 μM) had improved postischemic recovery, whereas co-perfusion with PI3Kα inhibitor, PI-103 (0.1 μM), abolished the EET-mediated effect. In contrast, blocking of PI3Kβ or PI3Kγ isoforms failed to inhibit EET-mediated cardioprotection. In addition to the improved post-ischemic recovery, increased levels of p-Akt, decreased calcineurin activity and decreased translocation of proapoptotic protein BAD to mitochondria were noted in EET-treated hearts. Perfusion of 11,12-EET to Kir6.2 deficient mice (pmK(ATP)) failed to improve postischemic recovery, decrease calcineurin activity and translocation of proapoptotic protein BAD, however increased levels of p-Akt were still observed. Patch-clamp experiments demonstrated that 11,12-EET could not activate pmK(ATP) currents in myocytes pre-treated with PI-103. Mechanistic studies in H9c2 cells demonstrate that 11,12-EET limits anoxia-reoxygenation triggered Ca(2+) accumulation and maintains mitochondrial ΔΨm compared to controls. Both PI-103 and glibenclamide (10 μM, pmK(ATP) inhibitor) abolished EET cytoprotection.

Conclusion: Together our data suggest that EET-mediated cardioprotection involves activation of PI3Kα, upstream of pmK(ATP), which prevents Ca(2+) overload and maintains mitochondrial function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8,11,14-Eicosatrienoic Acid / analogs & derivatives*
  • 8,11,14-Eicosatrienoic Acid / pharmacology
  • Animals
  • Calcium / metabolism
  • Cardiotonic Agents / pharmacology*
  • Cell Line
  • Class Ia Phosphatidylinositol 3-Kinase / metabolism*
  • Heart / drug effects*
  • Hypoxia
  • Isoenzymes / metabolism
  • KATP Channels / metabolism*
  • Membrane Potential, Mitochondrial / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myocardial Reperfusion Injury / metabolism
  • Myocardial Reperfusion Injury / physiopathology
  • Myocardial Reperfusion Injury / prevention & control
  • Myocardium / enzymology
  • Myocardium / metabolism*
  • Sarcolemma / enzymology
  • Sarcolemma / metabolism*


  • Cardiotonic Agents
  • Isoenzymes
  • KATP Channels
  • 11,12-epoxy-5,8,14-eicosatrienoic acid
  • Class Ia Phosphatidylinositol 3-Kinase
  • 8,11,14-Eicosatrienoic Acid
  • Calcium