title: The effects of phosphodiesterase-5 inhibitor sildenafil against post-resuscitation myocardial and intestinal microcirculatory dysfunction by attenuating apoptosis and regulating microRNAs expression: essential role of nitric oxide syntheses signaling.
abstract: BACKGROUND
  Recent experimental and clinical studies have indicated the cardioprotective role of sildenafil during ischemia/reperfusion (I/R) injury. Sildenafil has been shown to attenuate postresuscitation myocardial dysfunction in piget models of ventricular fibrillation. This study was designed to investigate if administration of sildenafil will attenuate post-resuscitation myocardial dysfunction by attenuating apoptosis and regulating miRNA expressions, furthermore, ameliorating the severity of post-microcirculatory dysfunction.
  
  
  METHODS
  Twenty-four male pigs (weighing 30 ± 2 kg) were randomly divided into groups, sildenafil pretreatment (n = 8), saline (n = 8) and sham operation (sham, n = 8). Sildenafil pretreatment consisted of 0.5 mg/kg sildenafil, administered once intraperitoneally 30 min prior to ventricular fibrillation (VF). Eight minutes of untreated VF was followed by defibrillation in anesthetized, closed-chest pigs. Hemodynamic status and blood samples were obtained at 0 min, 0.5, 1, 2, 4 and 6 h after return of spontaneous circulation (ROSC). Surviving pigs were euthanatized at 24 h after ROSC, and hearts were removed for analysis by electron microscopy, western blotting, quantitative real-time polymerase chain reaction (PCR), and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Intestinal microcirculatory blood flow was visualized by a sidestream dark-field imaging device at baseline and 0.5, 1, 2, 4, and 6 h after ROSC.
  
  
  RESULTS
  Compared with the saline group, the sildenafil group had a higher 24-hour survival (7/8 versus 3/8 survivors, p < 0.05) and a better outcome in hemodynamic parameters. The protective effect of sildenafil also correlated with reduced cardiomyocyte apoptosis, as evidenced by reduced TUNEL-positive cells, increased anti-apoptotic Bcl-2/Bax ratio and inhibited caspase-3 activity in myocardium. Additionally, sildenafil treatment inhibited the increases in the microRNA-1 levels and alleviated the decreases in the microRNA-133a levels which negatively regulates pro-apoptotic genes. At 6 h after ROSC, post-resuscitation perfused vessel density and microcirculatory flow index were significantly lower in the saline group than in the sildenafil group.
  
  
  CONCLUSIONS
  The major findings of this study are as follows: (1) sildenafil improved post-resuscitation perfusion of the heart, and thus reduced cardiac myocyte apoptosis and improved cardiac function; (2) sildenafil treatment inhibited the increases in the microRNA-1 levels, but alleviated the decreases in the microRNA-133a levels.
authors.affiliation: Department of Emergency Medicine, Beijing Chao-yang Hospital, Capital Medical University, Beijing, 100020, China. zqian604@163.com.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Emergency Medicine, Beijing You-yi Hospital, Capital Medical University, Beijing, 100050, China. 13520240749@163.com.
authors.forename: Guoxing
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Emergency Medicine, Beijing Chao-yang Hospital, Capital Medical University, Beijing, 100020, China. 2000ywei@sina.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Yuan
authors.affiliation: Department of Emergency Medicine, Beijing Chao-yang Hospital, Capital Medical University, Beijing, 100020, China. wu007838@sina.com.
authors.forename: Junyuan
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Emergency Medicine, Beijing Chao-yang Hospital, Capital Medical University, Beijing, 100020, China. wmm0327@126.com.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Emergency Medicine, Beijing Chao-yang Hospital, Capital Medical University, Beijing, 100020, China. lcscyyy@163.com.
authors.forename: ChunSheng
authors.initials: C
authors.lastname: Li
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001784:Blood Gas Analysis; D016887:Cardiopulmonary Resuscitation; D053148:Caspase 3 / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D006439:Hemodynamics / Q000187:drug effects; D007422:Intestines / Q000098:blood supply*; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008833:Microcirculation / Q000187:drug effects*; D009206:Myocardium / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D058986:Phosphodiesterase 5 Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D000068677:Sildenafil Citrate / Q000494:pharmacology*; D016019:Survival Analysis; D034421:Sus scrofa; D016276:Ventricular Function / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D035683:MicroRNAs; D058986:Phosphodiesterase 5 Inhibitors; D051028:bcl-2-Associated X Protein; D009569:Nitric Oxide; D000068677:Sildenafil Citrate; D019001:Nitric Oxide Synthase; D053148:Caspase 3; D006152:Cyclic GMP