title: [Effects of hypoxia combined-exercise on blood viscosity and cardiac function of rats].
abstract: OBJECTIVE
  To study the effects of hypoxia alone or combined-exercise on blood viscosity and cardiac function of rats.
  
  
  METHODS
  22 wistar rats were divided into 3 groups: I normoxic control; II hypoxia and III hypoxia-combined exercise. Rats of II and III groups were subjected to hypobaric hypoxia for 5 weeks (23 h/day). They were first brought to simulated 4 000 m altitude, where rats of the III group were forced to swim for 1 h/day (6 days/week). Then the animals were ascent to 5 000 m. Cardiac function were detected by polygraph, the blood viscosity was assayed by E-viscosimeter, 99mTc radiolabelled frog red blood cell was used to measure the cardiac output.
  
  
  RESULTS
  Hypoxia alone caused an increase in blood hematocrit (Hct) and viscosity. Cardiac function of the left and right ventricles, especially +/- dp/dt(max) was also increased. Hypoxia-combined-exercise did not cause further increase in Hct, while the blood viscosity was decreased. Cardiac function increased further in both ventricles and the cardiac output was increased by 20% after hypoxia-combined-exercise.
  
  
  CONCLUSIONS
  During acclimatization to hypoxia, moderate exercise can decrease the blood viscosity and increase the cardiac function. These changes may be advantageous in delivering oxygen to tissues and may be favorable for promoting acclimation to high altitude.
authors.affiliation: Department of Pathophysiology, College of High Altitude Military Medicine, Third Military Medical University, Chongqing 400038, China.
authors.forename: Fu-Yu
authors.initials: FY
authors.lastname: Liu
authors.forename: Qing-Yuan
authors.initials: QY
authors.lastname: Huang
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Gao
authors.forename: Wen-Xiang
authors.initials: WX
authors.lastname: Gao
mesh_terms: D000531:Altitude; D000818:Animals; D001794:Blood Pressure; D001809:Blood Viscosity; D002302:Cardiac Output; D006400:Hematocrit; D000860:Hypoxia / Q000097:blood*; D051381:Rats; D017208:Rats, Wistar; D013550:Swimming; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right