| Objective: Hypoxia induced pulmonary hypertension was caused byhypoxia vascular endothelial cell injury, vascular endothelial factor synthesisand secretion of various vasodilation balance disorders, leading to earlypulmonary vasoconstriction and in the late of pulmonary vascular remodeling.ACE-AngⅡ-AT１shaft, besides can cause lung small artery contraction canbe cause pulmonary vascular wall thickening and pulmonary vascularremodeling, pulmonary hypertension caused by chronic hypoxia has played avery important role in the process. Estradiol (E2) the protective material isgradually increasing in pulmonary vascular system. Because it can reduce avariety of causes of pulmonary vascular endothelial cells and smooth musclecell function damage, to improve vascular remodeling and diastolic bloodvessels, but the specific mechanism has not yet fully understood. This studyaims to establish long-term chronic hypoxic pulmonary hypertension ratsmodel, research on E2to intervene, hypoxia changes in pulmonaryhypertension rats pulmonary artery pressure and plasma and lung tissue ACEactivity, AngⅡcontent, AT1content changes. Whether the function of E2inrat pulmonary hypertension through the ACE－AngⅡ－AT１shaft, forpulmonary hypertension E2supplements provide theoretical basis fortreatment.Method:1Model building: sixty SD rats were divided randomly into1shamoperation group,2ovariectomy (OVX) group,3Hypoxia group,4OVX+Hypoxia group,5OVX+E2group,6OVX+Hypoxia+E2group. After a weekadaptive feeding, group2,4and6were opened the abdominal cavity, foundalong the oviduct ovarian, ligation under the ovaries fallopian tubes andnutrient vessels, ovaries removed, close the abdominal cavity, gentamicin to prevent infection, U suture of the skin. Group1only open the abdominalcavity, and then suture. Normal feeding one week, after waiting for woundhealing in hypoxia. Application of homemade organic glass anaerobic tank,the anaerobic tank24h continuous supply air and nitrogen gas atmosphericmixed gas, the oxygen concentration of oxygen box was controlled by oxygenmonitoring control system (10±0.5)%, CO2concentration less than0.5%；Then the rats of group3,4,6were placed in the hypoxic chamber, the rats ofgroup1,2,5were kept in the room air, and the rats were put in the same roomwith the same diet feeding.2Long-term changes in hypoxic pulmonary hypertension rats: Meanpulmonary artery pressure (mPAP), was measured by right-heart catheterize-tion, right ventricular hypertrophy index (RVHI) was calculated by the ratio ofright ventricle to the left ventricle plus septum, and hypoxic pulmonaryvascular remodeling (HPSR) was observed by microscope.3The content of angiotensin Ⅱ(AngⅡ) in lung tissue and serum wasmeasured by radio-immunity assay.4The concentration of angiotensin converting enzyme（ACE） in serumand lung tissue were measured by ultraviolet spectroscopy assay.5The content of Angiotensin II receptor-1in lung tissue was measuredby Western blotting and RT-PCR.6The content of Angiotensin II receptor-1in lung tissue and angiotensinconverting enzyme in pulmonary artery were measured by RT-PCR.Results:1Established rat model of PAH successfully: After eight weeks, comp-ared with group1, group3’s mPAP increased significantly, in conformity withthe pressure of pulmonary artery high pressure level; the mPAP of Group4’srats was more high; although the mPAP of group6was increased, but waslower than group3and group4significantly; the mPAP of group2and group5did not change.2Right ventricular morphology changes of long-term hypoxia pulmonaryhypertension rats: Blood vessel walls in lungs are thicken obviously, smooth muscle cells (SMC)of pulmonary small artery increased, the membrane(PAMT) thickening and luminal narrowing; and right ventricular hypertrophy,right ventricule hypertrophy became to develop significantly after eight weeksin group3, the difference is statistically significant. Group4of even more; thechange of pulmonary artery wall structure in group6was between group1and3; group2and5had normal pulmonary artery wall structure.3The change of Ang Ⅱ content in serum and lung tissue and the activityof ACE changes in lung tissue, serum, pulmonary artery: the content ofangiotensin Ⅱ (Ang Ⅱ) in lung tissue and serum was measured by ultravioletspectroscopy. The concentration of angiotensin converting enzyme（ACE） inserum, lung tissue, pulmonary artery was measured by ultravioletspectroscopy assay: Compared with group1, the expression level of ACE ingroup2, group3and group4was increased significantly, and increased by theincreasing of the group; group5and6’s did not change. The concentration ofangiotensin converting enzyme（ACE） in pulmonary artery was measured byRT-PCR: Compared with the group1, the expression level of ACE in group2,group3and group4increased significantly, and increased by the increasing ofthe group; group5and6’s did not change.4The expression of AT1in rat lung tissue: the content of angiotensin IIreceptor-1was measured by Western blotting: Compared with group1, theexpression level of AT1in group2, group3and group4was increasedsignificantly, and increased by the increasing of the group; group5and6’s didnot change. The content of angiotensin II receptor-1mRNA level wasmeasured by RT-PCR: compared with group1, the expression level of AT1mRNA in group2, group3and group4was increased significantly, andincreased by the increasing of the group; group5and6’s did not change.Conclusions:1Under hypoxia condition, the AT1content of rats’ lung tissue increasedobviously. The Ang II content in both rats’ serum and lung tissue increasedrespectively, as the ACE activity in serum, pulmonary artery and lung tissueall rose respectively. 2The ACE activity of purely castrated rats’ serum, pulmonary artery andlung tissue enhanced, and the combining and releasing of AngⅡ increased, asthe AT1protein content of lung tissue and mRNA’s expression bothincreased.3Compared with the rats living in the purely low oxygen environmentand the purely castrated rats, the ACE－AngⅡ－AT1axis’ activity of thecastrated rats living in the hypoxia environment represented higher, with theACE activity of the serum, pulmonary artery and lung tissue enhanced, thecombining and releasing of AngⅡ increased, and the AT1protein content oflung tissue and mRNA’s expression both increased.4E2could effectively reduce the mPAP, ventricular hypertrophy,vascular remodeling and ACE－AngⅡ－AT１shaft activity of the rats ofhypoxic pulmonary hypertension, purely castrated increased. Speculation E2of hypoxic pulmonary hypertension prevention of vascular remodeling may bepartly by cutting the ACE of lung tissue and the expression of AT1receptorreducing ACE-AngⅡ-AT1shaft activity. |
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