Objective:To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection.Methods: Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n=8). Myocardial injury was judged in accordance with serum levels of cTnⅠ and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium.Cx43mRNA was detected byin situhybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting.Results:The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P<0.05). However, LEP produced a significant increase in Cx43 protein level (P<0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P<0.05).Conclusions:LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.

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Objective:To explore the effects of smoking on lung function and physical fitness of college students.Method:168 college students on September 30, 2020 were selected as the research subjects by convenient sampling. According to whether they had been smoking for more than 3 years in the past or (and) now, they were divided into smoking group (66 cases, 39.3%) and non-smoking group (102 cases, 60.7%). The general demographic data, body composition, health fitness and lung function of all the included subjects were collected, and the health status of the two groups were compared, the relationship between lung function and healthy physical fitness in the smoking group was analyzed, and the influencing factors of forced vital capacity (FVC), forced expiratory volume in the first second (FEV 1) and expiratory vital capacity (EVC) were also analyzed. Results:The peak expiratory flow rate (PEF) of male college students in smoking group was lower than that of non-smoking group [(9.37±1.72) vs (10.04±1.69) L/s] ( F=5.051, P=0.026). The standing time with eyes closed and one foot of smoking group was longer than that of non-smoking group [(87.2±49.1) vs (63.6±39.7) s] ( F=9.327, P=0.003). The number of sit ups per minute of female college students in smoking group was less than that in non-smoking group [(39.5±7.5) vs (49.2±12.5) times/min] ( F=5.189, P=0.029). The peak inspiratory flow rate (PIF), FVC, FEV 1, EVC and PEF in the smoking group were positively correlated with grip strength, back muscle strength, number of sit ups, push ups, standing high jump and standing long jump ( P<0.001); through the analysis of relevant data, the estimation formula of lung function and health fitness items was obtained. Conclusion:Smoking is harmful to college students′ lung function and physical fitness.