A noval rat model for enhancing hypoxia tolerance

  AIM  To explore a new rat model for rapid improvement of hypoxia tolerance.

  METHODS  Small animal hypobaric chamber was used to simulate different barometric heights. The survival rate was obserred in SD rats after adapting to 4500 m for 10 h, returning to the ground for 1 h, and then staying at 7620 m for 24 h. The survival rate of SD rats after fasting for 24 h, 48 h, 72 h and staying at 7620 m for 24 h were also obserred and the myocardial autophagy flux of rats after fasting for 72 h was detected.

  RESULTS  The 4500 m hypoxic preconditioning improved the survival rate of rats staying at 7620 m for 24 h (P < 0.05); The survival rate of rats staying at 7620 m for 24 h after fasting for 24 h, 48 h and 72 h was significantly increased (P < 0.01); Fasting for 24 h combined with 4500 m preconditioning made the survival rate of rats staying at 7620 m for 24 h reached 100% (P < 0.01). In addition, the survival rate of rats staying at 7620 m for 24 h was affected by the age of rats, and the survival rate of younger rats was higher (P < 0.01). The results of Western blot showed that the expression of Beclin-1 (P < 0.01), the ratio of LC3-II to LC3-I increased (P < 0.01) and the expression of p62 protein decreased (P < 0.01) in the myocardium of rats after fasting for 72 hours, indicating that myocardial autophagy flux was inreased.

  CONCLUSION  Fasting preconditioning can be used as a new rat model to rapidly improve hypoxia tolerance, and the causal relationship between increased myocardial autophagy and hypoxia tolerance needs to be further studied.