Mitochondrial KATP channel activation reduces anoxic injury by restoring mitochondrial membrane potential

M. Xu, Y. Wang, A. Ayub, M. Ashraf

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

Mitochondrial membrane potential (ΔΨm) is severely compromised in the myocardium after ischemia-reperfusion and triggers apoptotic events leading to cell demise. This study tests the hypothesis that mitochondrial ATP-sensitive K+ (mitoKATP) channel activation prevents the collapse of ΔΨm in myocytes during anoxia-reoxygenation (A-R) and is responsible for cell protection via inhibition of apoptosis. After 3-h anoxia and 2-h reoxygenation, the cultured myocytes underwent extensive damage, as evidenced by decreased cell viability, compromised membrane permeability, increased apoptosis, and decreased ATP concentration. Mitochondria in A-R myocytes were swollen and fuzzy as shown after staining with Mite Tracker Orange CMTMRos and in an electron microscope and exhibited a collapsed ΔΨm, as monitored by 5,5′,6,6′-tetrachloro-1,1′,3,3′- tetraethylbenzimidazolcarbocyanine iodide (JC-1). Cytochrome c was released from mitochondria into the cytosol as demonstrated by cytochrome c immunostaining. Activation of mitoKATP channel with diazoxide (100 μmol/l) resulted in a significant protection against mitochondrial damage, ATP depletion, cytochrome c loss, and stabilized ΔΨm. This protection was blocked by 5-hydroxydecanoate (500 μmol/l), a mitoKATP channel-selective inhibitor, but not by HMR-1098 (30 μmol/l), a putative sarcolemmal KATP channel-selective inhibiter. Dissipation of ΔΨm also leads to opening of mitochondrial permeability transition pore, which was prevented by cyclosporin A. The data support the hypothesis that A-R disrupts ΔΨm and induces apoptosis, which are prevented by the activation of the mitoKATP channel. This further emphasizes the therapeutic significance of mitoKATP channel agonists in the prevention of ischemia-reperfusion cell injury.

Original languageEnglish (US)
Pages (from-to)H1295-H1303
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume281
Issue number3 50-3
StatePublished - Oct 1 2001
Externally publishedYes

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Keywords

  • ATP
  • Apoptosis
  • Cytochreme c
  • Myocytes
  • Permeability transition pore

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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