The Effect And Mechanism Of Different Intensity Exercise On The Heart Under Low Concentration Ozone Exposure

Objective:To clarify the effects of different intensity exercises and different frequency exposures on the myocardial tissue of rats in a mild ozone pollution environment(Ie under low concentration ozone exposure).Explore the path and molecular mechanism of myocardial injury caused by ozone combined exercise.Provide scientific basis for guiding outdoor sports under polluted weather.Methods:The male SD rats that can learn treadmill exercise were selected to be included in the experiment,and a single and triple ozone exposure compound exercise model was established.The experimental animals in the two models are divided into the following two groups:clean air combined with different intensity exercise groups(Air+0m/min group,Air+10m/min group,Air+15m/min group,Air+20m/min group)and ozone exposure combined with different intensity exercise groups(O₃+0 m/min group,O₃+10m/min group,O₃+15 m/min group,O₃+20 m/min group).The former is to put the rat in a clean environment and run on the animal treadmill at speeds of 0 m/min,10 m/min,15m/min and 20m/min for 1h.The latter is to place the rat on the animal treadmill in the gas poisoning chamber,keeping the ozone concentration in the poisoning chamber at 0.14 ppm,and performing the speed at 0 m/min,10 m/min,15 m/min and 20 m/min running for 1 h.The rats in the single ozone exposure combined exercise model were intervened according to the above method,and in the three ozone exposure combined exercise model,the rats were intervened according to the above method for 3 consecutive days.48 hours after the completion of the model,the rats were anesthetized with 3%sodium pentobarbital,and whole blood and serum were collected from the abdominal aorta.Subsequently,the right lobe of the lung was lavaged with normal saline,and the alveolar lavage fluid was collected.Finally,samples of myocardial tissue and lung tissue were collected,some of which were fixed for pathological examination,and the rest were frozen at-80?.Use automatic blood cell analyzer and automatic biochemical analyzer to detect blood routine and blood biochemistry.ELISA method detects serum and tissue levels of inflammatory factors such as TNF-?,IL-1,IL-6,IL-8,serum levels of myocardial injury markers and myocardial injury-related humoral factors,as well as lung injury-related levels in alveolar lavage fluid index.Detection of ROS in myocardial tissue by chemifluorescence method.Colorimetric and ELISA methods to detect oxidative stress indicators such as 8-OHd G,MDA,SOD,GSH-Px in serum and tissues.Detect MRCC-IV,ATP content and mitochondrial membrane potential in mitochondria in myocardial tissue by ELISA,bioluminescence and JC-1 respectively.TUNEL method to detect cardiomyocyte apoptosis.Western-Blot method to detect the expression of bcl-2,bax,caspase-3,caspase-9,KEAP1,PGAM5,AIFM1,p-AIFM1 in myocardial tissue.Observe the activation of cardiomyocyte apoptosis and oxeiptosis pathway by ozone combined exercise.Results:(1)After a single ozone combined exercise,cTnl in myocardial tissue was significantly reduced;exercise and ozone synergistically lead to a significant increase in MYO;ozone combined with moderate-intensity exercise(15 m/min,20 m/min) resulted in a significant increase in AST.Pathological examination revealed that the overall structure of the myocardial tissue was basically normal,the myocardial fiber gap was significantly enlarged,and a small amount of inflammatory cell infiltration was seen in this tissue.After three combined exposures,cTnl in myocardial tissue was significantly reduced;MYO was significantly increased.Pathological examination revealed that with the increase of exercise intensity,the myocardial tissue appeared serious structural abnormalities,the fibrous space was significantly widened,and there was slight bleeding.(2)After a single ozone compound exercise,exercise and ozone synergistically lead to a significant increase in ROS and 8-OHdG;SOD and GSH-Px are significantly reduced;TNF-?is significantly increased;exercise and ozone synergistically lead to IL-1 and IL-6,IL-8 and IL-10 increased significantly.After three combined exposures,the changes in oxidative stress and inflammatory factors were consistent with a single ozone compound exercise,but there was no interaction between exercise and ozone.(3)After a single compound exposure,the synergy of motion and ozone led to a significant decrease in Ang II,a significant increase in NE,a significant increase in EPI,ET-1,ANP,a significant decrease in NO and PGE-2,and a significant increase in TG,CHO,HDL-C,and LDL-C.After three compound exposures,serum EPI,ET-1,ANP increased significantly,NO,PGE-2 and HDL-C decreased significantly,TG and CHO decreased significantly,and exercise and ozone antagonists induced LDL-C increased significantly.(4)After a single compound exposure,pathological examination revealed that with the increase in exercise intensity,the overall structure of the lung tissue was severely abnormal,the alveolar interstitium and lung interstitium were significantly thickened,inflammatory cells infiltrated,and mild congestion was observed.Exercise and ozone in lung tissues synergistically mediate a significant increase in ROS;TNF-?,IL-6,IL-8 are significantly increased;exercise and ozone cause a significant increase in IL-1;serum liver function indicators ALT,AST,ALP,I-BIL,T-BIL,TBA were all significantly increased,and D-BIL was significantly decreased;the serum renal function indexes CRE,BUN,and UA were all significantly increased.After three compound exposures,pathological examination found that the lung tissue structure was more severely damaged,and some alveolar cavities were atrophy.Exercise and ozone in lung tissues synergistically mediate the significant increase of MDA and ROS;IL-1,IL-6,IL-8 significantly increase;exercise and ozone synergistically lead to a significant increase of TNF-?;in serum liver function indexes,only ALP increased significantly in the ozone-combined low-intensity exercise(10 m/min)group,and exercise and ozone played an antagonistic effect;the ozone-combined medium-intensity exercise (20 m/min) group T-BIL increased significantly;the serum renal function index BUN was significant Increased,exercise and ozone antagonism induced a significant decrease in CRE and UA.(5)The results of TUNEL experiment show that after a single compound exposure,the apoptotic rate of cardiomyocytes caused by exercise and ozone was significantly increased.Ultra-microstruct structure observation found that the myocardial mitochondrials vacuolated severely.The indicators of mitochondrial damage in rats were detected,and it was found that the synergy between exercise and ozone led to a significant decrease in MRCC-IV,a decrease in MMP,and a significant decrease in ATP.The expression of KEAP1 and PGAM5 in the"oxeiptosis"cell death path mediated by ROS increased significantly with the intensity of motion,AIFM1 gradually increased,AIFM1 increased significantly after the ozone composite medium intensity movement (20m/min),p-AIFM1decreased significantly,and the"oxeiptosis"cell death path was activated.Conclusion:(1)Moderate and low-intensity exercise under mild ozone pollution will not induce obvious myocardial necrosis in rats,but it can cause inflammatory cell infiltration,abnormal tissue structure,oxidative stress,and increased levels of inflammatory cytokines in the myocardium,showing random changes.The trend of increasing exercise intensity.(2)Ozone combined exercise can lead to systemic inflammation.Serum oxidative stress indicators and myocardial injury-related neuro-humoral factors increase,and lung tissues show pathological changes and inflammation.And the changes intensify with the increase of exercise intensity,these indicators may play an indirect role in inducing myocardial injury.(3)Single and triple ozone compound exercises have the same influence on most indicators,and the three ozone compound exercises have more serious damage to rats.In addition,a single ozone compound exercise can induce the body's lipid metabolism disorder and abnormal liver and kidney function,while three ozone compound exercises can induce oxidative stress in lung tissues.Exposure frequency can also affect the interaction of ozone and exercise on certain indicators.(4)Ozone combined exercise can lead to abnormal structure and function of myocardial mitochondria,which in turn induces mitochondrial-dependent apoptosis of myocardial cells.It can also mediate the activation of the"oxeiptosis"pathway by inducing the increase of ROS in the myocardium.