Establishment of animal model of stimulating altitude training

Bing ZHANG; Yunhe ZHOU; Ran ZHAO

ABSTRACT

BACKGROUND:

As a method to effectively improve organic tolerance and velocity, altitude training has been gradually accepted by the coaches,and it is a problem to be solved to find the optimal altitude.

OBJECTIVE:

To establish rat models of stimulating altitude training, and observe the changes of myocardial cell structure in the altitude training, so as to provide scientific animal models for the physiological studies of altitude training, and provide more scientific theoretical evidence for the altitude training of athletes.

DESIGN:

Based on the division of altitude region in aerospace medicine,the experimental animals were divided into different altitude training groups and control groups. Morphological characters of cellular and subcellular structures were observed under electron microscope, the biochemical analysis of cardiac troponin T were performed, and then the myocardial injury was completely analyzed from two pathways of morphology and biochemistry.

SETTING:

Laboratory of Sports and Human Sciences, Tsinghua University.MATERIALS The experiments were carried out in the Laboratory of Sports and Human Sciences, Tsinghua University from January 2000 to December 2002. Totally 372 male SD rats were used. The experimental materials included hypobaric oxygen chamber, Japanese H-500 transmission electron microscope and the kit for testing serum cardiac troponin T index.

METHODS:

After adaptive swimming training for 1 week, all the 372 rats were randomly divided into 9 groups and 54 subgroups, only 6 groups of them were analyzed in this experiment, including stimulating acute altitude hypoxia training at 4 000 m group (n=32), hypoxia without training group (n=24), stimulating acute altitude training at 4 000 m followed by reoxygen training for 1 week group (n=32), stimulating acute altitude training at 4000 m followed by reoxygen training for 2 weeks group (n=32), increasing altitude training group (n=32) and plain training control group (n=24). Rats in the plain training control group lived and trained in normal conditions,and those in the other groups all trained with swimming in the stimulating altitude environment for 4 weeks. They were trained for 7 days every week,once a day and 60 minutes for each time for 4 weeks. The serum cardic troponin T index of rats was detected and observed with enzyme-linked immunoabsorbent assay (ELISA). After stimulating acute altitude training at 4 000 m for 4 weeks followed by reoxygen training for 2 weeks, the rats were killed, and a small piece of myocardial tissue was taken from left and right ventricles, then double-stained with uranyl acetate and lead citrate,and the ultrastructure of the sections was observed with Japanese H-500 transmission electron microscope.MAIN OUTCOME

MEASURES:

The serum cardiac troponin T index of rats trained at different altitude, and the results of spectrum and observation of myocardial ultrastucture under electron microscope were mainly observed.

RESULTS:

① Changes of body mass The myocardial increasing rate in the hypoxia training group was significantly different from those in the hypoxia without training control group and plain training control group (P ＜ 0.01), and there was also significant difference between the latter two groups (P ＜ 0.05). The increasing rate of body mass was significantly different among the hypoxia training group, hypoxia without training control group and plain training control group (22.41％, 28.14％, 33.48％,P ＜ 0.01-0.05). ② Results of cardiac troponin T Compared with the hypoxia without training group, the value of cardiac troponin T in the hypoxia training groups was significantly different, and significantly increased with weeks of training (P ＜ 0.01). During the hypoxia altitude training below 4 000 m for 1-4 weeks, the value of cardiac troponin T ranged in creased from 0.09 to 0.128 μg/L, and it gradually recovered to 0.09 μg/L after reoxygen training in plain for 2 weeks. ③ The results of observation under electron microscope showed that after acute hypoxia training at 4 000 m for 4 weeks, myocardial mitochondrial structure occurred mild swelling with the prolongation of training, and for the rats received reoxygen training in plain for 2 weeks, the thick and thin myofilaments of myocardial fibers formed light and dark bands were clear and distinct, and the myotomes arranged orderly, besides clustered or scattered glycogen granules, a great amount of mitochondria also existed among muscular bundles, no swelling, degeneration of vacuoles, lysis necrosis, interstitial edema and other pathological changes were observed.

CONCLUSION:

It is safe to train rats at any altitude below 4 000 m. The acute exercise training of great intensity directly at 4 000 m will cause the mild injury of cardiac subcellular structure, and the increase of cardiac troponin T concentration. The training by means of increasing altitude has slighter influence on the myocardial injury, and the recovery after training is also faster.