| 1 ObjectiveSeeking for the best age of hypoxic intervention and the best duration of hypoxia,and on the basis of the protective effect of intermittent hypoxia to study the effects of intermittent hypoxia and regular exercise on myocardial contractile protein actin and myosin,and myocardial pump function of drosophila.2 MethodsThe virgin W1118 female flies were collected and respectively divided into three groups by age:young-hypoxia group(YH),middle—age-hypoxia group(MH)and old-hypoxia group(OH).The duration of hypoxia of each group was ranging from 0 to 14 days.The optimal duration and age of intermittent hypoxia and regular exercise was chosen by the test results of heart failure model.The virgin W1118 female flies were collected and divided into four groups:Normoxic Control group(NC),Normoxic exercise group(NE),Hypoxic control group(HC)and Hypoxic exercise group(HE).The hypoxia and excersice interventions were started from 3-week-old to 6-week-old.The environment oxygen content of HC and HE were 6%,6h per day,the daily duration of exercise of NE and HE were 2.5h.Detecting the myocardial pump function,myocardial contraction protein content,climbing ability,lifespan,activity monitoring and life quality of each group after all the protocol.3 Results3.1 Result of heart failure rateThe heart failure rate of drosophila increasec with age,the heart failure rate of MH and OH were decreased with the extension of hypoxic duration,while YH revealed the oposite result.3.2 Result of transmission electron microscopeThe cardiac myofilaments of group NC,NE,HE are arranged regularly,while the structure of cardiac myofilaments of group HC are vague.The number of mitochondria of group NE and HC are more than NC and HE.3.3 Result of immunofluorescenceComparing with group NC,the cardiac diameter of group NE is lager while group HC is smaller,but the actin and myosin proteins of them are all arranged more regular than group NC,however,the arrangement of the actin and myosin proteins are loose and irregular.3.4 Result of western blotThe actin and myosin content of group NE,HC and HE are all more than group NC.3.5 Result of myocardial systolic functionThe diastolic diameter of group HC is lower than group NC,NE and HE dramatically(P<0.05),and group NE is higher than group NC dramatically(P<0.05).The systolic diameter of group HC is lower than group NC and HE dramatically(P<0.05).The fraction shortening of NE is higher than NC(P<0.01).3.6 Result of climbing abilityThe climbing speed of group NE,NH,and HE are all faster than group NC(P<0.05).3.7 Result of activity monitoringThe total sleep duration at night of group HC and HE are longer than NC(P<0.05),the sleep bout number at night of HC is lower than NC(P<0.01).The total time of activity at daytime of NE is higher than NC,HC and HE(P<0.05),and HC is lower than NC(P<0.05).The awakening/sleep value and activity amount among active duration is higher than NC,HE and HE(P<0.05).The activity amount among active duration of HC is higher than NC and HE(P<0.05),and the active duration at daytime of HC is lower than NC(P<0.05).3.8 Result of lifespanThe maximum lifespan of HC is higher than NC and NE(P<0.01.The average lifespan of HC is higher than NC,NE and HE(P<0.01),and the average lifespan of HE is higher than NC and NE(P<0.05).4 Conclusion4.1 The heart failure rate of drosophila increasec with age,the heart failure rate of middle age and old age drosophila were decreased with the extension of hypoxic duration.4.2 Regular excercise can defer the age-induced reduction of myocardial contraction protein and mitochondria content,maintain the cardiac diastolic,increase the climbing ability,enhance the activity amount of drosophila.4.3 Intermittent hypoxia can defer the age-induced reduction of myocardial contraction protein and mitochondria content,and the myocardial fibers arranged more compact.Furthermore,intermittent hypoxia can increase the climbing ability,extend lifespan,improve sleep quality at night. |
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