Mechanisms by which epoxyeicosatrienoic acids (EETs) elicit cardioprotection in rat hearts

Garrett J. Gross, Anna Hsu, John R. Falck, Kasem Nithipatikom

Research output: Contribution to journalArticle

81 Citations (Scopus)

Abstract

Cytochrome P450 (CYP) epoxygenases and their arachidonic acid (AA) metabolites, the epoxyeicosatrienoic acids (EETs), have been shown to produce reductions in infarct size in canine myocardium following ischemia-reperfusion injury via opening of either the sarcolemmal KATP (sarcKATP) or mitochondrial KATP (mitoKATP) channel. In the present study, we subjected intact rat hearts to 30 min of left coronary artery occlusion and 2 h of reperfusion followed by tetrazolium staining to determine infarct size as a percent of the area at risk (IS/AAR, %). The results demonstrate that the two major regioisomers of the CYP epoxygenase pathway, 11,12-EET (2.5 mg/kg, iv) and 14,15-EET (2.5 mg/kg, iv) significantly reduced myocardial infarct size (IS/AAR, %) in rats as compared with control (41.9 ± 2.3%, 40.9 ± 1.2% versus 61.5 ± 1.6%, respectively), whereas, a third regioisomer, 8,9-EET (2.5 mg/kg, iv) had no effect (55.2 ± 1.4). The protective effect of pretreatment with 11,12- and 14,15-EETs was completely abolished (61.9 ± 0.7%, 58.6 ± 3.1%, HMR; 63.3 ± 1.2%, 63.2 ± 2.5%, 5-HD) in the presence of the selective sarcKATP channel antagonist, HMR 1098 (6 mg/kg, iv) or the selective mitoKATP channel antagonist, 5-HD (10 mg/kg, iv) given 10 min after 11,12- or 14,15-EET administration but 5 min prior to index ischemia. Furthermore, concomitant pretreatment with 11,12- or 14,15-EET in combination with the free radical scavenger, 2-mercaptopropionyl glycine (2-MPG), at a dose (20 mg/kg, iv) that had no effect on IS/AAR (57.7 ± 1.3%), completely abolished the cardioprotective effect of 11,12- and 14,15-EETs (58.2 ± 1.6%, 61.4 ± 1.0%), respectively. These data suggest that part of the cardioprotective effects of EETs in rat hearts against infarction is the result of an initial burst of reactive oxygen species (ROS) and subsequent activation of both the sarcKATP and mitoKATP channel.

Original languageEnglish (US)
Pages (from-to)687-691
Number of pages5
JournalJournal of Molecular and Cellular Cardiology
Volume42
Issue number3
DOIs
StatePublished - Mar 2007

Fingerprint

Acids
Cytochrome P-450 Enzyme System
KATP Channels
Free Radical Scavengers
Coronary Occlusion
Reperfusion Injury
Arachidonic Acid
Glycine
Infarction
Reperfusion
Canidae
Reactive Oxygen Species
Coronary Vessels
Myocardium
Ischemia
Myocardial Infarction
14,15-epoxy-5,8,11-eicosatrienoic acid
11,12-epoxy-5,8,14-eicosatrienoic acid
Staining and Labeling
mitochondrial K(ATP) channel

Keywords

  • 11,12-EET
  • 14,15-EET
  • 8,9-EET
  • CYP450
  • Mito- and sarcK channels
  • Reactive oxygen species

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this

Mechanisms by which epoxyeicosatrienoic acids (EETs) elicit cardioprotection in rat hearts. / Gross, Garrett J.; Hsu, Anna; Falck, John R.; Nithipatikom, Kasem.

In: Journal of Molecular and Cellular Cardiology, Vol. 42, No. 3, 03.2007, p. 687-691.

Research output: Contribution to journalArticle

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N2 - Cytochrome P450 (CYP) epoxygenases and their arachidonic acid (AA) metabolites, the epoxyeicosatrienoic acids (EETs), have been shown to produce reductions in infarct size in canine myocardium following ischemia-reperfusion injury via opening of either the sarcolemmal KATP (sarcKATP) or mitochondrial KATP (mitoKATP) channel. In the present study, we subjected intact rat hearts to 30 min of left coronary artery occlusion and 2 h of reperfusion followed by tetrazolium staining to determine infarct size as a percent of the area at risk (IS/AAR, %). The results demonstrate that the two major regioisomers of the CYP epoxygenase pathway, 11,12-EET (2.5 mg/kg, iv) and 14,15-EET (2.5 mg/kg, iv) significantly reduced myocardial infarct size (IS/AAR, %) in rats as compared with control (41.9 ± 2.3%, 40.9 ± 1.2% versus 61.5 ± 1.6%, respectively), whereas, a third regioisomer, 8,9-EET (2.5 mg/kg, iv) had no effect (55.2 ± 1.4). The protective effect of pretreatment with 11,12- and 14,15-EETs was completely abolished (61.9 ± 0.7%, 58.6 ± 3.1%, HMR; 63.3 ± 1.2%, 63.2 ± 2.5%, 5-HD) in the presence of the selective sarcKATP channel antagonist, HMR 1098 (6 mg/kg, iv) or the selective mitoKATP channel antagonist, 5-HD (10 mg/kg, iv) given 10 min after 11,12- or 14,15-EET administration but 5 min prior to index ischemia. Furthermore, concomitant pretreatment with 11,12- or 14,15-EET in combination with the free radical scavenger, 2-mercaptopropionyl glycine (2-MPG), at a dose (20 mg/kg, iv) that had no effect on IS/AAR (57.7 ± 1.3%), completely abolished the cardioprotective effect of 11,12- and 14,15-EETs (58.2 ± 1.6%, 61.4 ± 1.0%), respectively. These data suggest that part of the cardioprotective effects of EETs in rat hearts against infarction is the result of an initial burst of reactive oxygen species (ROS) and subsequent activation of both the sarcKATP and mitoKATP channel.

AB - Cytochrome P450 (CYP) epoxygenases and their arachidonic acid (AA) metabolites, the epoxyeicosatrienoic acids (EETs), have been shown to produce reductions in infarct size in canine myocardium following ischemia-reperfusion injury via opening of either the sarcolemmal KATP (sarcKATP) or mitochondrial KATP (mitoKATP) channel. In the present study, we subjected intact rat hearts to 30 min of left coronary artery occlusion and 2 h of reperfusion followed by tetrazolium staining to determine infarct size as a percent of the area at risk (IS/AAR, %). The results demonstrate that the two major regioisomers of the CYP epoxygenase pathway, 11,12-EET (2.5 mg/kg, iv) and 14,15-EET (2.5 mg/kg, iv) significantly reduced myocardial infarct size (IS/AAR, %) in rats as compared with control (41.9 ± 2.3%, 40.9 ± 1.2% versus 61.5 ± 1.6%, respectively), whereas, a third regioisomer, 8,9-EET (2.5 mg/kg, iv) had no effect (55.2 ± 1.4). The protective effect of pretreatment with 11,12- and 14,15-EETs was completely abolished (61.9 ± 0.7%, 58.6 ± 3.1%, HMR; 63.3 ± 1.2%, 63.2 ± 2.5%, 5-HD) in the presence of the selective sarcKATP channel antagonist, HMR 1098 (6 mg/kg, iv) or the selective mitoKATP channel antagonist, 5-HD (10 mg/kg, iv) given 10 min after 11,12- or 14,15-EET administration but 5 min prior to index ischemia. Furthermore, concomitant pretreatment with 11,12- or 14,15-EET in combination with the free radical scavenger, 2-mercaptopropionyl glycine (2-MPG), at a dose (20 mg/kg, iv) that had no effect on IS/AAR (57.7 ± 1.3%), completely abolished the cardioprotective effect of 11,12- and 14,15-EETs (58.2 ± 1.6%, 61.4 ± 1.0%), respectively. These data suggest that part of the cardioprotective effects of EETs in rat hearts against infarction is the result of an initial burst of reactive oxygen species (ROS) and subsequent activation of both the sarcKATP and mitoKATP channel.

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