title: Cardioprotection by PI3K-mediated signaling is required for anti-arrhythmia and myocardial repair in response to ischemic preconditioning in infarcted pig hearts.
abstract: Although the phosphatidyl-inositol-3-kinase (PI3K)/Akt pathway is essential for conferring cardioprotection in response to ischemic preconditioning (IP), the role of PI3K/Akt signaling in the infarcted heart for mediating the anti-arrhythmic effects in response to IP remains unclear. We explored the involvement of PI3K/Akt in the IP-like effect of connexin 43 and proangiogenic factors with particular regard to its role in protecting against ischemia-induced arrhythmia, heart failure, and myocardial remodeling. Groups of pigs were administered phosphate-buffered saline (PBS) or LY294002 solution. Before induction of myocardial infarction (MI), pigs were grouped according to whether or not they underwent IP. Next, all animals underwent MI induction by ligation of the left anterior descending (LAD) coronary artery. Myocardial tissues from the pig hearts at 7 days after MI were used to assess myocardium myeloperoxidase and reaction oxygen species, infarct size, collagen content, blood vascular density, expression of Akt, connexin 43, and proangiogenic growth factors, using spectrophotometer, histology, immunohistochemistry, real-time RT-PCR, and western blot. At 7 days after MI, IP significantly reduced animal mortality and malignant ventricular arrhythmia, myocardial inflammation, infarct size, and collagen content, and improved cardiac function and remodeling; use of the PI3K inhibitor LY294002 diminished these effects. In parallel with a decline in Akt expression and phosphorylation by MI, LY294002 injection resulted in significant suppression of connexin 43 and proangiogenic factor expression, and a reduction of angiogenesis and collateral circulation. These findings demonstrate that the cardioprotective effects of IP on antiventricular arrhythmia and myocardial repair occur through upregulation of PI3K/Akt-mediated connexin 43 and growth factor signaling.
authors.affiliation: 1] Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Department of Cardiology, Qilu Hospital of Shandong University, Ji'nan, People's Republic of China [2] Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Su
authors.affiliation: Department of Cardiology, Dahua Hospital, Shanghai, People's Republic of China.
authors.forename: Lan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Shaoheng
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Jiahong
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Nannan
authors.initials: N
authors.lastname: Chen
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Qunlin
authors.initials: Q
authors.lastname: Gong
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Tang
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Cardiology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Department of Cardiology, Qilu Hospital of Shandong University, Ji'nan, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhong
authors.affiliation: Department of Cardiology, Dahua Hospital, Shanghai, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yan
mesh_terms: D000818:Animals; D002867:Chromones; D019194:Ischemic Preconditioning; D009025:Morpholines; D009203:Myocardial Infarction / Q000378:metabolism*; D009206:Myocardium / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015398:Signal Transduction / Q000502:physiology*; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D002867:Chromones; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one