| Objective: In this study,the effects of Aldehyde dehydrogenase 2（ALDH2）on pulmonary vascular remodeling and pulmonary vascular tone in rats with hypoxic pulmonary arterial hypertension,and identify the mechanism by which calcineurin（CAN）and Nuclear factor of activated T cells（NFATc）CAN/NFATc3 mediates the calcium activated potassium channel KCa in hypoxic pulmonary arterial hypertension.Methods: SPF-grade rats were randomly divided into normoxia Adeno associated virus（AAV9）AAV9-null group（NC）,normoxia AAV9-ALDH2 overexpression group（NA）,hypoxia AAV9-null group（HC）and hypoxia AAV9-ALDH2 overexpression group（HA）.The rat model of hypoxic pulmonary hypertension was constructed by tracheal injection transfected with the corresponding AAV9 according to the group and placed in a hypoxic chamber after 2 weeks.After 4 weeks of hypoxia,the ratio of pulmonary artery acceleration time（PAT）/pulmonary artery ejection time（PET）and right ventricular free wall thickness（RVFW）,and the catheter was inserted into the left common carotid artery and right common jugular vein to measure mean blood pressure（MBP）and right ventricular pressure（RVSP）.The right ventricular free wall and the left ventricle and septum of rats were cut off and drained,and the right ventricular hypertrophy index（RVHI）was calculated.Pathological sections were taken from the right lower lung of rats,and some pulmonary artery vessels were fixed by electron microscopy,stained by HE,Ki67 and Tunel,to observe and calculate the vascular remodeling of small pulmonary arteries,lung tissue proliferation,apoptosis and pulmonary artery vessel microstructure.The pulmonary artery vessels in each group were isolated,placed in a K-H liquid bath and connected to a tension transducer,and the NFATc2 inhibitor CSA（10umol/L）,NFATc3 inhibitor VIVIT（40umol/L）and KCa inhibitor ITX（100nmol/L）were added to observe the changes in pulmonary vascular diastolic tone in each group.Finally,rat lung tissue proteins containing pulmonary artery vessels were extracted to observe the expression of ALDH2,CAN,NFATc1,NFATc2,NFATc3 and KCa proteins.Results:1.The general condition of rats: the rats in HC showed reduced food intake,depression,less weight gain,wasted body shape and cyanosis in the peripheral terminal circulation,while the rats in HA showed significant improvement in the above conditions.2.Changes in pulmonary artery ultrasound,hemodynamics and right ventricular specific gravity: compared with the NC,rats in the HC had a decreased PAT/PET and a significantly increased RVFW,RVHI and RVSP;compared with the HC,rats in the HA had a significantly increased PAT/PET and a significantly decreased RVFW,RVHI and RVSP.Compared with the HC,the rats in the HA showed a significant increase in PAT/PET,and a significant decrease in RVFW,RVHI and RVSP,while there was no significant abnormal change in MBP in each group.3.Small pulmonary artery remodeling: compared with the NC,the HC after 4 weeks of hypoxia had a significantly thickened pulmonary artery wall,increased Ki67 expression,decreased apoptotic protein expression,and increased percentage of lumen occlusion with irregular arrangement of cells;compared with the HC,the HA had a significantly decreased percentage of lumen occlusion,decreased Ki67 expression,increased apoptotic protein expression,and compared with the HC,the vascular in HA showed a significant decrease in the percentage of lumen blockage,a decrease in Ki67 expression,an increase in apoptotic protein expression,and a thinning of the wall and regular cell arrangement.4.Changes in ultrastructure of pulmonary artery vessels: compared with NC,mitochondrial swelling increased,mitochondrial cristae disappeared and disorganized in HC;compared with HC,mitochondrial swelling was reduced and mitochondrial morphology tended to be normal in HA.5.Differences in diastolic tone of isolated pulmonary artery vascular rings in each group: compared with the NC and NA,diastolic tone was significantly reduced in the HC after pharmacological intervention with CSA,VIVIT and ITX;compared with the HC,diastolic tone was significantly increased in the HA.6.The protein expression of ALDH2,CAN,NFATc1,NFATc2,NFATc3 and KCa in lung tissue: compared with the NC,the protein expression of CAN and NFATc3 in HC rats was significantly increased,while the protein expression of ALDH2 and KCa was significantly decreased;compared with the HC,the protein expression of CAN and NFATc3 in HA was significantly decreased,and the protein expression of ALDH2 and KCa protein expression were significantly increased in the HA,while NFATc1 and NFATc2 protein expression show no significantly differences in each group.Conclusion:1.ALDH2 significantly improved right ventricular function and right ventricular remodeling in rats with hypoxic pulmonary hypertension,increased PAT/PET ratio,inhibited proliferation and promoted apoptosis of pulmonary artery smooth muscle cells,reduced mitochondrial swelling due to hypoxia,maintained the function of mitochondrial morphology,and improved pulmonary vascular remodeling.2.ALDH2 significantly increased pulmonary vascular diastolic tone caused by CSA,VIVIT and ITX.3.ALDH2 has a protective effect on hypoxic pulmonary hypertension,which may be related to the protein expression of CAN/NFATc3 and KCa. |
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