| BackgroundSpace technology is an important sign for national strength, scientific and technological level. Being joy and pride, China is the third to complete success of the manned flight in the world. However, it is a focus that how to ensure astronauts health in long-duration missions, including muscle wastage,bone loss and cardiovascular deconditioning,which should be acutely awared. Microgravity is an extreme environment inducing relevant adaptive change in the cardiovascular system, especially the heart which is the mainly involved targeting organ of weightlessness. The cardiac function, cardiac systolic and ultrastructure are adapted to the weightlessness.Currently the countermeasures have limited success for cardiovascular deconditioning, despite the multiple use and various kinds.Cardiovascular deconditioning has limited manned space flight development in medium and long duration missions. Acupuncture has been used as medical means since antiquity in China and the effect of acupuncture therapy is satisfactory and prompt for cardiovascular disease. Thus, for the development of Space Medico-Engineering with Chinese characteristics, it is necessary to carry out research on the effects in treating cardiovascular disease induced by the weighlessness with acupuncture.Objective1 Tail-suspension rats were used animal model of simulated microgravity, observe the effects of cardiac function, cardiac atrophy, myocardial ultrastructure, ET, ANP and HSP70 and illustrate the mechanisms of myocardial injury induced by simulate microgravity.2 Tail-suspension rats were used animal model of simulated microgravity, study the effects in treating cardiovascular deconditioning, including cardiac function, cardiac atrophy, myocardial ultrastructure, ET, ANP and HSP70 with acupuncture.3 Compare the different effect of Neiguan(PC6) and Sanyinjiao(SP6) and investigate the possible mechanism of acupuncture.MethodTail-suspension rats were used anmial model of simulated microgravity. A total of 40 male Wistar rats were randomly divided into normal control group, model group, Neiguan(PC6) group, and Sanyinjiao(SP6) groups, with 10 rats in each group. Rats in normal control group are feed as normal without treatment. Rats in model group are tail-suspension four weeks and fixed in a plate with 30 degrees for 30min. Rats in PC6 group are tail-suspension four weeks and done by electroacupuncture at PC6 in a plate with 30 degree qod for 30min.Rats in SP6 group are tail-suspension four weeks and done by electroacupuncture at SP6 in a plate with 30 degrees for 30min. Four weeks later, left ventricular function were evaluated by echocardiography. Lactate dehydrogenase, succinate dehydrogenase, ATPase activities in myocardium,endothelin and atrial natriuretic peptide in serum were measured by colorimetry. The morphological changes were observed by light microscopy after H.E. staining and electron microscope. Methods Immunohistochemistry staining is used to detect HSP70 in myocardium.Result1 Effects of electroacupuncture on cardiac function in rats under simulated weightlessness measured by echocardiography in each groupCompared with normal control group, IVSd, IVSs, LVPWd and FS in model group obviously decreased (P≤0.05), LVDd and EF significantly decreased (P＜≤0.01), while Heart rate increased (P≤0.05), difference is not marked among the other datas, including LVDs, LVPWs, LVEDV, LVESV and SV. There was no significant difference between normal control group and PC6 group (P＞0.05). Compared with normal control group, LVDd in PC6 group significantly increased (P≤0.01), difference is not marked among the other datas (P＞0.05).2 Effects of electroacupuncture on myocardial enzymes in rats under simulated weightlessnessCompared with normal group, the ATPase activity in model group was significantly decreased (P＜0.05). Compared with model group, the ATPase activity in PC6 group was little increased (P＞0.05), while the ATPase activity in SP6 group was obviously increased (P≤0.05). There was no significant difference between PC6 group and SP6 group (P＞0.05). Compared with normal group, the ATPase activity in PC6 group and SP6 group were both little decreased (P＞0.05).Compared with normal group, the SDH activity in model group was little increased (P>0.05). Compared with model group, the SDH activity in PC6 group and SP6 group were both little decreased (P＞0.05). There was no significant difference between PC6 group and SP6 group (P＞0.05). Compared with normal group, the SDH activity in PC6 group and SP6 group were both little decreased (P＞0.05).Compared with normal group, the LDH activity in model group was obviously increased (P≤0.05). Compared with model group, the LDH activity in PC6 group and SP6 group were both significant decreased (P＜0.05). There was no significant difference between PC6 group and SP6 group (P>0.05). Compared with normal group, the LDH activity in PC6 group and SP6 group were both little decreased (P>0.05).3 Effects of electroacupuncture on morphology in myocardiumThe normal structure of myocardium was observed in normal control group. The arrangement of myocardial fibers was disorganized in the model group. Plenty of myocardial fibers were broken and dying. The myocardial cells are normal, the nucleus are oval and located mainly in the center of the cells in the PC6 and SP6 groups. The arrangement of myocardial fibers was well organized. The interstitial cells were sightly edema.4 Effects of electroacupuncture on ultrastructure in myocardiumTransimission electron miscroscope found that the myofilaments of myocardial cells in normal control group were well arrange. There were abundant and normal mitochondria in normal control group. Compared with normal control group,the myofilaments were dissolved in model group,with swollen mitochondria and blurred cristae, showing distinct pathological changes. Compared with model group, there was a improvement in myofilament dissolution in PC6 group and SP6 group. A little couple of mitochondria were changed, such as double-layer structrue of mitochondria membrane integrity, ridge structure disappeared,vacuolization of mitochondria. There was no significant difference between PC6 group and SP6 group.5 Effects of electroacupuncture on endothelin and atrial natriuretic peptide in serumCompared with normal group, the content of endothelin in serum in model group was obviously increased (P＜0.05). Compared with model group, the content of endothelin in serum in PC6 group and SP6 group were both significantly decreased (P＜0.05). There was no significant difference between PC6 group and SP6 group (P>0.05). Compared with normal group, the the content of endothelin in serum in PC6 group and SP6 group were both little decreased (P＞0.05).Compared with normal group, the content of atrial natriuretic peptide in serum in model group was little increased(P>0.05). Compared with model group,the content of atrial natriuretic peptide in serum in PC6 group and SP6 group were both little decreased (P＞0.05). There was no significant difference between PC6 group and SP6 group (P＞0.05). Compared with normal group, the the content of atrial natriuretic peptide in serum in PC6 group and SP6 group were both little decreased (P>0.05).6 Effects of electroacupuncture on expression of HSP70 in myocardiumThe expression of HSP70 in myocardium was found tan particulates in the cytoplasm and nucleus. The expression of HSP70 in myocardium was obsevered within the cytoplasm and nucleus in normal control group. The expression of HSP70 in myocardium was up-regulated within the cytoplasm and nucleus in model group, which stained more deeply than the expression of HSP70 in normal control group (P＞0.05). Compared with normal group, the expression of HSP70 in PC6 group and SP6 group were both up-regulated (P>0.05). Compared with the model group, the expresson of HSP70 in PC6 group was down-regulated within the cytoplasm and nucleus (P≤0.05), while the expresson of HSP70 in SP6 group was little decrease (P＞0.05). There was no significant difference between PC6 group and SP6 group (P＞0.05).Conclusion1 Simulated weightlessness mainly results in decrease of the left ventricular function and changing of cardiac structural electroacupuncture can increase the LVDd, IVSd, FVSs, LVPWd, FS, EF and decrease the heart rates,having protective effects on simulated weightlessness rats cardiac function.2 Metabolic dysfunction that lead anaerobic metabolism existed in myocardial cell of rats under simulated weightlessness.Electroacupuncture has functions in up-regulating the myocardial oxygen supply, ATPase activity and decrease LDH activity.3 There was an adaptation change of structure and ultrastructure in myocardial cell under simulated weightlessness. Electroacupuncture has a improvement of structure and ultrastructure in myocardial cell, which maybe contribute to its protective effect on myocardial injury.4 The content of ET and ANP in serum were little increased in simulated weightlessness rats.Simulated weightlessness results in anoxia and ischemic injury, the expression of HSP70 increased.Electroacupuncture has a improvement of anoxia and ischemic injury and decreased the content of ET and ANP. There was no significant difference between PC6 group and SP6 group.
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