title: PKA-mediated eNOS phosphorylation in the protection of ischemic preconditioning against no-reflow.
abstract: OBJECTIVE
  To investigate whether ischemic preconditioning (IP) can reduce myocardial no-reflow by activating endothelial (e-) nitric oxide synthase (NOS) via the protein kinase A (PKA) pathway.
  
  
  RESULTS
  In a 90-min ischemia and 3-h reperfusion model, minipigs were assigned into sham, ischemia-reperfusion (IR), IR+IP, IR+IP+L-NNA (an eNOS inhibitor, 10mg·kg(-1)), IR+IP+H-89 (a PKA inhibitor, 1.0μg·kg(-1)·min(-1)), IR+L-NNA, and IR+H-89 groups. IP pretreatment improved cardiac function and coronary blood flow, decreased the activities of creatine kinase by 36.6% after 90 min of ischemia and by 32.8% after 3 h of reperfusion (P<0.05), reduced the no-reflow areas from 49.9% to 11.0% (P<0.01), and attenuated the infarct size from 78.2% to 35.4% (P<0.01). IP stimulated myocardial PKA activities and the expression of PKA and Ser(133) phosphorylated (p-) cAMP response element-binding protein (CREB) in the reflow and no-reflow myocardium, and enhanced the activities of constitutive NOS and the phosphorylation of eNOS at Ser(1179) and Ser(635) in the no-reflow myocardium. IP suppressed the expression of tumor necrosis factor-α and P-selectin, and attenuated cardiomyocytes apoptosis by regulating the expression of Bcl-2 and caspase-3 in the reflow and no-reflow myocardium. The eNOS inhibitor L-NNA completely canceled these beneficial effects of IP without any influence on PKA activity, whereas the PKA inhibitor H-89 partially blocked the IP cardioprotective effects and eNOS phosphorylation at the same time.
  
  
  CONCLUSIONS
  IP attenuates myocardial no-reflow and infarction after ischemia and reperfusion by activating the phosphorylation of eNOS at Ser(1179) and Ser(635) in a partly PKA-dependent manner.
authors.affiliation: Department of Cardiology, Fuwai Hospital and Cardiovascular Institute, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100037, China.
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Li
authors.forename: Yu-Tong
authors.initials: YT
authors.lastname: Cheng
authors.forename: Yue-Jin
authors.initials: YJ
authors.lastname: Yang
authors.forename: Xian-Min
authors.initials: XM
authors.lastname: Meng
authors.forename: Jing-Lin
authors.initials: JL
authors.lastname: Zhao
authors.forename: Hai-Tao
authors.initials: HT
authors.lastname: Zhang
authors.forename: Yong-Jian
authors.initials: YJ
authors.lastname: Wu
authors.forename: Shi-Jie
authors.initials: SJ
authors.lastname: You
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Wu
mesh_terms: D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006439:Hemodynamics; D019194:Ischemic Preconditioning; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D017682:Myocardial Stunning / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D054318:No-Reflow Phenomenon / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D010766:Phosphorylation; D013552:Swine; D013556:Swine, Miniature
chemical_list: D015415:Biomarkers; D052250:Nitric Oxide Synthase Type III; D017868:Cyclic AMP-Dependent Protein Kinases