Effects Of Cold Stress And Cold Adaptation On Adenosine Triphosphatase Activity, The Content Of Ca²⁺ And Free Radical Metabolism In Swimming Rats

Objective: Winter swimming is an exercise with high intensity in cold environment. During this exercise, metabolism rate of the body raises and oxygen consumption increases. Long-term regular winter swimming exercise is thought to promote blood circulation, improve the functional status of the body, improve immunity, enhance physical fitness, and thus prevent age-related diseases. But in recent years cases of sudden death caused by winter swimming have been increased, these deaths are mainly due to cardiac or cerebrovascular causes and thromboembolic diseases. There are very little reach about the changes of the body under cold stress and cold adaptation exercise and body reaction to different temperature and exercise intensity. Therefore, we need more in-depth research into the impact of winter swimming on body function. In this article, we used the response of the body in winter swimming under different water temperature and time as the experimental data , and established animal model of winter swimming using the method of cold stress and cold adaptation swimming in rats , analyzing the effect of two patterns of winter swimming exercise on radical metabolism , ATP activity and Ca ²⁺content of the body, understanding the double role of cold stress and cold adaptation exercise on the physical state of the body, providing basic datas for the changes of body under cold adaptation exercise , and providing the scientific basis about winter swimming fitness for enthusiasts, Thus to prevent injuries caused by winter swimming.Methods: 30 Male Sprague-Dauley (SD) rats were randomly divided into three groups, control group (n = 10), cold stress sport group (n = 10), cold-adapted sport group (n = 10). Control group: NO training and were killed at the 7nd week . Cold stress sport groups: At the end of the 6 nd week, adaptive swimming training 3 days, once a day, water temperature 30℃, 15min. At the 7nd Week swimmed once, water temperature 8℃, 8min and were killed immediately after exercise. Cold-adapted sport groups: adaptive swimming 3 days, once a day, water temperature 30℃, 15min. Formal training: starting temperature 30℃, 40min, once a day. but from the 2th day, the temperature was decreased 2℃,and the exercise time was shorten 3min each day , trained 6 days a week for 2 weeks. From the 3thweek, the temperature was kept at 10℃and 5min for 4 weeks. At the 7 nd Week swimmed once, water temperature 8℃, 8min and were killed immediately after exercise. All the rats weighed once a week. After the execution, take the tissue of hearts and brains. Treat the tissues by methods of homogenate and centrifugation. Test the following indexes: MDA content, SOD activity, Na-K-ATPase activity, Ca-ATPase activity and Ca ²⁺content.Results:1 Weight change: From the 3thweek to the end of the experiment, the mean of body weight in the cold-adapted sport group is significantly lower than that in the control group and the cold stress sport group (P <0.01);But there are no significant differences between the control group and the cold stress sport group(P>0.05). At end of the experiment, weight growth rate of the control group and the cold stress sport group (52.6%, 51.1%) is significantly higher than the cold-adapted sport group (27.0%) (P <0.01).2 Oxidative stress indicators: The MDA content of the heart and the brain in the cold stress sport group (2.45±0.30 nmol / mgprot, 9.65±0.75 nmol / mgprot) is significantly higher than that in the control group (P <0.01); The MDA content of the heart and the brain in the cold-adapted sport group(1.82±0.29nmol/mgprot, 6.68±0.78nmol/mgprot) has no difference with that in the control group (P> 0.05), but is significantly lower than that in the cold stress sport group (P <0.01). The SOD activity of the heart and the brain in the cold stree sport group(95.22±29.92 U/mgprot,153.21±10.17 U/mgprot)is significantly lower than that in the control group (P <0.01); The SOD activity of the heart and the brain in the cold-adapted sport group(278.80±25.50 U/mgprot ,190.27±12.55 U/mgprot)has no difference with that in the control group (P> 0.05), but is significantly higher than that in the cold stress sport group (P <0.01).3 The ATPase activity and the Ca ²⁺content : The Na + -K + -ATPase activity of the heart and the brain in the cold stree sport group(1.58±1.14μmolpi/mgprot/hour,2.13±0.32μmolpi/mgprot/hour)is significantly lower than that in the control group (P <0.01); The Na + -K + -ATPase activity of the heart and the brain in the cold-adapted sport group; (1.98±0.15μmolpi/mgprot/hour,2.90±0.37μmolpi/mgprot/hour)has no difference with that in the control group (P>0.05), but is significantly higher than that in the cold stress sport group (P <0.01).The Ca ²⁺-ATPase activity of the heart and the brain in the cold stree group ( 2.35±0.20μmolpi/mgprot/hour ,1.33±0.19μmolpi/mgprot/hour)is significantly lower than that in the control group (P <0.01); The Ca ²⁺-ATPase activity of the heart and the brain in the cold-adapted sport group ( 2.67±0.23μmolpi/mgprot/hour , 1.72±0.21μmolpi/mgprot/hour ) has no difference with that in the control group (P>0.05), but is significantly higher than that in the cold stress sport group (P <0.01). The Ca ²⁺content of the heart and the brain in the cold stress sport group(95±6.01μmol/gprot,34±5.81μmol/gprot)is higher than that in the control group (P <0.05); The Ca ²⁺content of the heart and the brain in the cold-adapted sport group(89±5.67μmol/gprot ,29±4.85μmol/gprot)has no difference with that in the control group (P> 0.05), but is lower than that in the cold stress sport group (P <0.05).4 Correlation tests between MDA and ATPase: In the heart correlation coefficient between MDA and Na + -K + -ATPase is -0.726(P<0.01),shows negative correlation;In the heart correlation coefficient between MDA and Ca ²⁺-ATPase is -0.387(P<0.05),shows negative correlation. In the brain correlation coefficient between MDA and Na + -K + -ATPase is -0.697(P<0.01),shows negative correlation;In the brain correlation coefficient between MDA and Ca ²⁺-ATPase is -0.712(P<0.01),shows negative correlation.Conclusions:1 Long-term cold adapted swimming is very effective for weight control, and this could play a positive role on reducing the incidence of obesity-related diseases.2 Cold adapted swimming can significantly reduce damages caused by the lipid peroxidation, improve the capacity of antioxidant system, enhance the adaptability of exercise in cold water stress.3 The fall in ATP activity and cell calcium overload is related to free radical damage caused by oxidative stress. Through long-term antioxidant adaptation, cold adapted swimming can improve the activity of ATP and maintain normal calcium content in tissue.