title: Myocardial capillary angiogenesis and coronary flow in ischemia tolerance rat by adaptation to intermittent high altitude hypoxia.
abstract: OBJECTIVE
  To determine the effects of simulated intermittent high altitude hypoxia adaptation (IHA) on coronary capillary and coronary flow (CF) in rat hearts.
  
  
  METHODS
  Model of Langendorf-perfused isolated rat hearts were used to measure CF during ischemia-reperfusion, and immunoperoxidase staining assay and computer-aid morphometry analysis were conducted to determine the myocardial capillary densities. Cyclic GMP (cGMP) level in myocardium was measured by radio-immunoassay.
  
  
  RESULTS
  Pre-ischemia level of CF in IHA rats was higher (IHA28 13.4 mL/min+/-1.5 mL/min, IHA42 15.4 mL/min+/-2.0 mL/min, P < 0.01) than that of normoxic rats (11.0+/-0.8) mL/min, and the recovery of CF after ischemia-reperfusion was better in IHA rats. As an adaptive result, the myocardial capillary densities of the left ventricular myocardium in IHA rats were 1.5 times of those in normoxic control rats, but there was no apparent ventricular hypertrophy in IHA rats. Myocardial cGMP content (1.8+/-0.7) nmol/g in IHA rats were increased significantly compared with control rats (1.1+/-0.4) nmol/g, but cGMP level was not altered before and after ischemia-reperfusion in either group. It was also revealed that in isolated rat hearts perfused, myocardial function recovered better in IHA rats than that in normoxic control rats.
  
  
  CONCLUSIONS
  IHA adaptation increased the tolerance of rat hearts against subsequent ischemia-reperfusion injury, and increase in coronary circulation and angiogenesis might be the mechanisms of myocardium protected by IHA.
authors.affiliation: Health Science Center, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhong
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Zhu
authors.forename: Jun-Chen
authors.initials: JC
authors.lastname: Wang
authors.forename: Qi-Zhi
authors.initials: QZ
authors.lastname: Fang
authors.forename: Zhao-Nian
authors.initials: ZN
authors.lastname: Zhou
mesh_terms: D000222:Adaptation, Physiological; D000532:Altitude Sickness / Q000503:physiopathology*; D000818:Animals; D003326:Coronary Circulation / Q000502:physiology; D006152:Cyclic GMP / Q000378:metabolism; D000860:Hypoxia / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology*; D018919:Neovascularization, Physiologic; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology
chemical_list: D006152:Cyclic GMP