| Hypertension is a common disease in flying personnel and one of the most important risk factors for cardiovascular and cerebrovascular diseases. In recent years, the studies have shown that the composition ratio of hypertension increased significantly in hospitalized disease spectrum and hypertension has been one of the most common medical reasons inducing permanent grounding in military flying personnel. Hypertension is a chronic disease and needs life-long medication in most cases.Existing Air Force Flying Personnel Medical Examination Standard provides:the flying personnel with hypertension stage I who have good treatment effect, no obvious symptoms and good flight endurance is qualified. So how to solve the problems of medical identification of hypertension in the flying personnel and the flight with medicine in part of the flying personnel with hypertension has important significance for ensuring their health and flight safety. The flying personnel with hypertension in medicine in the two-seated low-performanced aircrafts (such as transport planes, helicopters and bombers) have been allowed to return to flying, but pilots of fighter and attack aircraft after taking medicine of lowering blood pressure at home and abroad in present are not allowed to fly. So we simulated hypertensive flying personnel under repeated+Gz exposure by using spontaneously hypertensive rats (SHR) model to observe arterial blood pressure change, the target organ damage (hearts, brains, kidneys, aortas), and the protective effect of telmisartan. It will provide experimental evidence for the protection of hypertensive pilots of fighter and attack aircraft and further amendments of the flying personnel medical examination standards.In this study,28-week-old male SHR and14-week-old male Wistar Kyoto rats (WKY) were randomly divided into six groups:seven SHR in SHR+Gz exposure group(SHR+Gz), seven SHR in SHR control group (SHR-C), seven SHR in telmisartan treatment SHR+Gz exposure group (TT-SHR+Gz), seven SHR in telmisartan treatment SHR control group (TT-SHR-C), seven WKY in WKY+Gz exposures group(WKY+Gz), and seven WKY in WKY control group (WKY-C). The telmisartan treatment group of SHR was given medicine since one week before centrifuge exposure through intragastric administration (30mg·kg-1·d-1) to control their SBP in normal range. The+Gz exposures were performed in+5Gz/10s and+9Gz/10s alternately with onset rate1G/s, and the total+Gz exposure time was94s, then the+Gz exposure was repeated after20min rest, total for7days. The control group rats didn’t expose to the+Gz. The specimens of the hearts, brains, kidneys and aortas of all the rats were collected after the experiment, treated by HE staining and observed by optical microscopy. The left ventricular myocardial hypertrophy index (LVMI) was measured. The apoptosis was observed with terminal deoxynucleotide transferase-mediated dUTP nick end labeling method (TUNEL) and the apoptotic index(AI) was counted.The main results are as follows:1、The study on the target organ damage of SHR after repeated+Gz exposure:(1) SBP in SHR+Gz at the moment of1h after the+Gz exposure was higher than that before experiment and than that in SHR-C from the first day to the seventh day of the experiment (P<0.01). At the moment of of6h after daily+Gz exposure, SBP in SHR+Gz could recover to the level before+Gz exposure.(2) The LVMI of SHR-C was significantly increased comparing with that of WKY-C (P<0.01). The LVMI of SHR+Gz was bigger than that of SHR-C (P<0.05). Under optical microscopy, the damage of myocardium, kidneys and cerebral cortex was found in SHR-C, and that in SHR+Gz was more severe than in SHR-C.(3) By TUNEL, the AI of ventricular myocardium, cerebral cortex and renal cortex cells in SHR-C was significantly more than in WKY-C (P<0.05), and that in SHR+Gz was more than in SHR-C.(P<0.05). Apoptotic cells were not found in the aortas of all the rats.2、The study on the protection of telmisartan to the damage of target organs in SHR after repeated+Gz exposure:(1) The telmisartan given to the rats through intragastric administration (30mg·kg-1·d-1) could control their SBP to normal range.(2) SBP in TT-SHR+Gz at the moment of1h after the+Gz exposure had transient decline on the first two days of+Gz exposure, but this situation disappeared from the third day. At the moment of6h after daily+Gz exposure, SBP could recover to the level before+Gz exposure.(3) There was no significant difference in the LVMI between TT-SHR-C and WKY-C (P>0.05). Under optical microscopy, no significant histological damage was found in TT-SHR-C and WKY-C.(4) By TUNEL, there was no significant difference in the AI of ventricular myocardium, cerebral cortex and renal cortex cells between TT-SHR-C and WKY-C (P>0.05), and apoptotic cells were not found in the aortas of the rats.The above results indicate that:Arterial blood pressure in the SHR increases furtherly after+Gz exposure and the damage of target organs (hearts, brains and kidneys) in the SHR can be aggravated by repeated+Gz exposure. Telmisartan can effectively reverse early target organ’s damage of SHR and repeated+Gz exposure does not increase the degree of target organs damage when the blood pressure is controlled in normal range. |
PDF Full Text Request