Effects Of Simulated Flight On The Secretion ET-1, HO-1and Oxidative Stress In Endothelial Cells

BACKGROUDFlight factors on the influence of the pilot cardiovascular disease, in recent years is one of the hot air medical research. Whether military aviation, or civil aviation are required to ensure flight safety first. But military aviation is the particularity of the civil aviation has more, involves the military operations. So once appear accident, not only causing casualties, but will also be greatly disrupt military tasks to complete. Modern high-performance fighter with continuous high positive acceleration (+Gz), high+Gz growth rate and other characteristics, to pilot the body requirements at almost the physiological limits, so vulnerable to low oxygen noise and vibration and other factors and cause psychological and physiological stress. A research report, China’s flight personnel30years old group atherosclerosis index to the general population40～50years old level, hint of coronary artery disease early time May10to15years. Foreign related research shows that, the United States a group underwent death of military and civil aviation accident pilot survey found that43.82%of cardiovascular anomalies pilot, of which37.6%coronary artery stenosis. Poland air force of229pilots check, most pilots have hyperlipidemia, including mild, moderate, and severe40.6%30.4%7.4%, and the average atherosclerosis (AS) index greater than5. The animal study shows,+Gz exposure can make high cholesterol diet rabbit serum lipid metabolism disorders, indicating that the positive acceleration exposure may accelerate the process of atherosclerosis. Repeat high+Gz exposure, can lead to big rat heart tissue vascular endothelial cells cell between cells adhesion molecule-1(ICAM-1) expressing increasing, the results show that+Gz cause myocardial injuries process, inflammation of the inevitable happens, may further aggravating+Gz to myocardial injuries. So the fighter planes fly high positive acceleration exposure, through many ways may cause endothelial cell injury, and speed up the pilot progression of atherosclerosis.G is for a gravity acceleration of the surface of the earth, in the aviation defined as one of the G in sea level flight aviation machine of lift and from the attractions of the earth and to attract strength phase equilibrium; And when vehicle change inertia, such as acceleration and deceleration or to the action of the straight line that will generate positive or negative G force. When the vehicle acceleration or climb, and lead to gravity from the top down, or the straight action of the centrifugal force, can produce is G force, produce the G forces and ground position there is no direct relationship with aircraft original position and direction and relevant, such as aircraft and ground close to the upside down to, even if the ground is also will produce below is G force. Relatively slow down or down and when the aircraft that gravity from down to up, can produce negative G force, this time the up and down with the ground position also there is no direct relationship. In fact in the life all the time to generate additional G forces, but most because too tiny so often neglected, if want to experience can use of high-speed obviously equipment or traffic tools, such as roller coaster or high speed railway, but this kind of way of G force produced in general the human body still can withstand range, and at any time for the high-speed action aircraft pilot on speaking, G is not be ignored in the force an important key to, and often mean life or death. The foundation of general human body+Gz endurance for4.0G or so, in charge of the effective measures to avoid resistance under+9.0Gz, already more than basic endurance of more than two times. And along with the development of the load resistance measures, the human body may also short tolerance of higher value and not appear+Gz syncope. This is far more than the human body of the endurance+based Gz exposure, is likely to human tissue injury or adverse effects. Animal centrifuge is the special equipment for simulated flight test on the surface of the earth, can precisely control+Gz value,+Gz growth rate and the role of air combat simulation time and action+Gz mode.In all kinds of damage factors effect, endothelial cell injury is atherosclerosis of the development process of key tumor-initiating link, it is both induction cells is effect cell, not only can sense the inflammatory signals, blood hormone levels, shear stress, pressure and other information, and can secrete a variety of blood vessels by active material of the information to make the response.Oxidative stress is to point to the body’s cells or to oxygen free radicals, as a representative of the oxidizing substances produced and eliminate the imbalance, or external oxide qualitative excess intake, leading to oxidative sex material accumulation in a cell and easy to cause the oxidation reaction condition. Oxidative stress induced endothelial cell injury mechanism is very complex, main show is oxygen free radicals of peroxidation. Because of the free radicals reaction causes cell membrane lipid peroxidation, protein and nucleic acid degeneration, cause irreversible damage. Endothelial oxidative damage is of the formation of the atherosclerosis tumor-initiating factors, membrane in smooth muscle cell proliferation and migration into the lining is its development important factors.Oxidative stress in endothelial cell injury atherosclerosis happened play an important role in the development of, it is mainly through oxidation, promote local inflammatory reaction induced by the change of blood vessels, and to participate in the genes affect signal transduction pathways involved in many aspects such as the occurrence of atherosclerosis development process. Superoxide dismutase (SOD) and malondialdehyde (MDA) is the body reaction to oxidative stress markers.Early atherosclerosis a pathological physiology change is mononuclear cells to vascular intima layer, activate and stimulate transitions of factor release. Already the in vitro confirmed, Endothelin1(ET-1) can be used as chemotactic agent mononuclear cells use, so Endothelin1May be atherosclerosis a tumor-initiating factor. Endothelin1is the most important in the epithelial tumour was the shrinkage within blood vessels factor, in vitro experiments, lead to the release of the ET-1reason is more, but the main think and vascular endothelial is impaired. Atherosclerosis for endothelial damaged cause ET-1increases, when its rise to certain degree coronary artery spasm can occur, and further damage endothelial cells make ET-1more rise. ET-1also can stimulate the transitions and vascular smooth muscle cell proliferation, so as to promote the process of atherosclerosis. ET-1through the strongly contraction blood vessels, and to promote the smooth muscle cell proliferation and thrombosis mechanisms such as the cause and accelerate atherosclerosis, restenosis.Other research shows that ET-1can stimulate the generation of reactive oxygen species through accelerated atherosclerosis process. So ET-1May through the above approaches are involved in endothelial cell injury and atherosclerosis formation.Heme oxygen and enzyme-carbon monoxide-cyclic guanosine monophosphate (HO-CO-cGMP) cell signal system, cardiovascular system in the adjustment.Heme oxygenase-1(HO-1), also known as the heat shock protein32(hsp32), is in the process of stress concentration significantly increased the presence of a stress protein, widely distributed in all kinds of organizations and cells. A lot of research shows that HO-1for oxidative damage caused by various diseases have to protect, in normal vascular smooth muscle cells and endothelial cells are low level expression, by oxidative stress stimulation produced high level, can restrain the occurrence of inflammation and endothelial cells of protection, saved it by oxidative stress damage. HO-1catalytic degradation of hemoglobin three product CO, bilirubin and iron protein is play cells to protect the role of the key molecules. CO and nitric oxide (NO) on the cardiovascular system has a similar effect, can activate soluble guanylyl cyclase (sGC), increase the cytoplasmic cGMP level, thus diastolic vascular smooth muscle, inhibiting platelet aggregation, smooth muscle cell proliferation and inflammatory reaction.HO-1/CO system compensatory and regulation through NOS/NO system and reduce ET-1expression, improve endothelial function.Although each product function have protection alone role, but cell protection is mainly the result of three synergy. When stress occurs, the moderate induction HO-1/CO system of expression, can maintain stable cells themselves, and to realize the protection of cells.Hemin commonly used to induce HO-1expression.OBJECTIVEThrough the special centrifuge simulated flying high positive acceleration processing of the New Zealand white rabbit as a model, take its aortic endothelial cells in culture of simulated flight experiment in rabbit aorta endothelial cells related cell factors HO-1level, CO content, cGMP content, ET-1content, SOD, MDA content. And then use the Hemin intervene, discusses the simulated flight to aortic endothelial cell injury influence and the probable protection mechanism of HO-1/CO system.METHODSAll New Zealand white rabbits in the same condition, the free drink, feeding, and keep the natural light, no bad factors, raising a week after laboratory environment to begin to experiment.16only clean level, health New Zealand big white rabbit randomly divided into two groups:blank control group only8, simulated flight experiment treatment group only8. This study included the method used for centrifuge simulation experiment made flight mode, centrifuge is simulated flight experiment in the ground for the acceleration of special equipment, can precisely control+Gz value,+Gz growth rate and the role of air combat simulation time and action+Gz mode. Simulated flight experiment treatment groups:New Zealand white rabbit into centrifuge from+7Gz,45s start centrifugal, every day increases by+0.5Gz,11days increase to+12Gz,45s, day12repeated1time, by day13using T model check+Gz endurance, growth rate averaged+1Gz/s, every time increases by+2Gz, exposure Gz value from12Gz start, to the expected after the G cost constant speed45s, then drop, two rotating rest between5min, pass to increase until the end tolerance, which appear to reduce animal heart half the normal. Blank control group:New Zealand white rabbit into centrifuge but not accept centrifugal experiment. In13days, each New Zealand white rabbit all press rabbit aorta endothelial cell separation method separation, the original generation cells for training.Above cells will be divided into three groups, Normal control group (n=8), the animal experiments blank control group aortic endothelial cells in low serum (2%) cells in growing the incubation12h; Simulated flight experiment dealing group (n=8), the animal experiments simulated flight treatment group in low serum aortic endothelial cells (2%) cells in growing the incubation12h; Simulated flight Hemin treatment group (n=8), the animal experiments simulated flight treatment group in low serum aortic endothelial cells (2%) cells in growing the incubation30min, and then to Hemin (10umol/L) incubation12h.Collect the cells and cell suspension liquid, observe the following indicators, ELISA experiment method to detect cell suspension liquid ET-1content, detection HO-1level, CO content, cGMP content, at the same time, detection cells suspension liquid respectively the MDA content and SOD activity.Statistical analyses of the study are performed using SPSS for Windows version13.0. Results are presented as means±sem,use T test analyze the two samples. A value of P<0.05is considered statistically significant.RESULTS1, Simulation experimental treatment with normal flight group compared to the aortic endothelial cell suspension liquid SOD significantly reduced (t=8.006, P<0.001), the content of MDA significantly increased (t=10.606, P<0.001), the above changes have significant differences. Hemin group and Simulation experimental treatment groupcompared, aortic endothelial cells SOD activity increased significantly, the difference was statistically significant (t=7.263, P<0.001); MDA content was significantly lower, the difference was statistically significant (t=6.211, P<0.001).2, Simulation experimental treatment group and flight blank compared, the content of ET-1significantly increased, the above changes have obvious statistical significance(t=75.424,P<0.001).Hemin group and Simulation experimental treatment group compared, aortic endothelial cells ET-1content was significantly lower, the difference was statistically significant(t=77.105,P<0.001).3, Simulation experimental treatment group and flight blank compared, the expression of HO-1significantly increased(t=32.441,P=<0.001), CO content increased significantly (t=11.719, P=0.000), cGMP content increased significantly (t=7.609, P=0.000), the above changes have significant differences. Hemin group and Simulation experimental treatment group compared, the expression of HO-1significantly increased(t=49.632,P=<0.001), CO content increased significantly(t=21.723,P<0.001), cGMP content increased significantly(t=6.644,P<0.001), the above changes have significant differences. CONCLUSION1, The simulated flight experiment high positive acceleration processing can influence the aortic endothelial cells oxidatie stress state, accelerate cell oxidative damage.2, The simulation experiment of high positive acceleration flight can promote the aortic endothelial cells ET-1release, with aortic endothelial cells may be impaired.3, Simulation experiment of high positive acceleration flight can promote the aorta cells HO-1level, CO content, content of cGMP that HO-1/CO system with the high expression may in flight to aortic endothelial cells of stress the protective effects of relevant.4,Hemin group, HO-1level, CO content, cGMP content release significant increase, the oxidative stress improved, ET-1the expression level is reduced, Hemin can stimulate cells that HO-1/CO system of high expression, may delay the body for stress in flight to aortic endothelial cell injury to provide certain reference value.