title: [N-acetylcysteine promoted aging through adjusting expression of cell cycle related protein in neonatal SD rat cardiomyocytes].
abstract: OBJECTIVE
  To observe the effects of N-acetylcysteine (NAC) on aging in neonatal SD rat cardiomyocytes and explore related mechanisms.
  
  
  METHODS
  Cultured cardiomyocytes were randomized assigned to 6 groups: 1-day, 5-day, 10-day, 1-day + NAC (1 mmol/L), 5-day + NAC (1 mmol/L) and 10-day + NAC (1 mmol/L). Flow cytometry was used to examine cell cycle. Real-time quantitative PCR and Western blot were used to determine mRNA and protein expression of p16INK4a, p21WAF1 and Rb gene. beta-galactosidase staining kit was used to investigate beta-galactosidase activity.
  
  
  RESULTS
  Numbers of cardiomyocytes resided in G(0)/G(1) phase were significantly higher in the group of 5-day + NAC and 10-day + NAC compared with 5-day, 10-day, respectively (P < 0.05). The mRNA and protein expression of p16INK4a and p21WAF1 were also significantly higher in the group of 5-day + NAC and 10-day + NAC compared with 5-day, 10-day, respectively (P < 0.05 or P < 0.01). The mRNA and protein expression of Rb was significantly lower in the group of 5-day + NAC and 10-day + NAC compared with 5-day, 10-day, respectively (P < 0.01). beta-galactosidase activity was not affected by NAC in the 1-day + NAC group but was significantly higher in 5-day + NAC and 10-day + NAC groups compared with the 5-day, 10-day groups (all P < 0.05).
  
  
  CONCLUSIONS
  NAC could promote aging through upregulating the expression of p16INK4a and p21WAF1 and inhibiting Rb phosphorylation in neonatal SD rat cardiomyocytes.
authors.affiliation: Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China.
authors.forename: Feng-xiang
authors.initials: FX
authors.lastname: Zhang
authors.forename: Ming-long
authors.initials: ML
authors.lastname: Chen
authors.forename: Bing
authors.initials: B
authors.lastname: Yang
authors.forename: Hong-wu
authors.initials: HW
authors.lastname: Chen
authors.forename: Ke-jiang
authors.initials: KJ
authors.lastname: Cao
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D002453:Cell Cycle; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D012333:RNA, Messenger; D000111:Acetylcysteine