Endothelial nitric oxide synthase plays an obligatory role in the late phase of ischemic preconditioning by activating the protein kinase C epsilon p44/42 mitogen-activated protein kinase pSer-signal transducers and activators of transcription1/3 pathway.
BACKGROUND
The role of endothelial nitric oxide synthase (eNOS) in ischemic preconditioning (PC) and cardioprotection is poorly understood. We addressed this issue using a genetic, rather than pharmacological, approach.


RESULTS
In the nonpreconditioned state, eNOS-/- mice exhibited infarct sizes similar to those of wild-type mice. A sequence of six 4-minute coronary occlusion/4-minute reperfusion cycles (ischemic PC) induced late PC in wild-type mice; genetic deletion of eNOS abrogated the cardioprotection induced by late PC. In wild-type mice, ischemic PC induced membranous translocation of protein kinase C (PKC) epsilon and an increase in pSer-MEK-1/2 and pTyr-p44/42 mitogen-activated protein kinase, nuclear pSer-signal transducers and activators of transcription (STAT)1 and pSer-STAT3, and nuclear STAT1/3 DNA binding activity, followed by upregulation of cyclooxygenase-2 protein and activity 24 hours later. All of these changes were abrogated in eNOS-/- mice. The NO donor diethylenetriamine/NO recapitulated the effects of ischemic PC.


CONCLUSIONS
In contrast to previous reports, we found that basal eNOS activity does not modulate infarct size in the nonpreconditioned state. However, eNOS is obligatorily required for the development of the cardioprotective effects of late PC and acts as the trigger of this process by activating the PKC epsilon-MEK-1/2-p44/42 mitogen-activated protein kinase pathway, leading to Ser-727 phosphorylation of STAT1 and STAT3 and consequent upregulation of STAT-dependent genes such as cyclooxygenase-2. The effects of eNOS-derived NO are reproduced by exogenous NO (NO donors), implying that nitrates can upregulate cardiac cyclooxygenase-2.
Xuan
Yu-Ting
YT
Institute of Molecular Cardiology, University of Louisville, Louisville, KY 40292, USA. ytxuan01@louisville.edu
Guo
Yiru
Y
Zhu
Yanqing
Y
Wang
Ou-Li
OL
Rokosh
Gregg
G
Bolli
Roberto
R
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D006973:Hypertension / Q000150:complications / Q000235:genetics; D019157:Ischemic Preconditioning, Myocardial; D048728:MAP Kinase Kinase Kinase 1 / Q000502:physiology; D048730:MAP Kinase Kinase Kinase 2 / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology; D009203:Myocardial Infarction / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology / Q000517:prevention & control*; D009569:Nitric Oxide / Q000502:physiology; D020030:Nitric Oxide Donors / Q000494:pharmacology / Q000627:therapeutic use; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III; D010766:Phosphorylation / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D050794:STAT1 Transcription Factor / Q000502:physiology; D050796:STAT3 Transcription Factor / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013047:Specific Pathogen-Free Organisms; D013312:Stress, Physiological / Q000503:physiopathology; D013997:Time Factors; D014226:Triazenes / Q000494:pharmacology / Q000627:therapeutic use
C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; D020030:Nitric Oxide Donors; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; C494080:Stat1 protein, mouse; C494087:Stat3 protein, mouse; D014226:Triazenes; D009569:Nitric Oxide; D004247:DNA; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D051744:Protein Kinase C-epsilon; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048728:MAP Kinase Kinase Kinase 1; D048730:MAP Kinase Kinase Kinase 2; C482619:Map3k2 protein, mouse