ABSTRACT
Objectives:The aim of this study was to observe whether transthoracic pulmonary artery denervation (TPADN) could reduce the pulmonary arterial pressure and attenuate pulmonary vascular remodeling in rats with pulmonary arterial hypertension induced by monocrotaline. Methods:Twenty-four healthy male SD rats were randomly divided into control group, sham operation group and operation group (n=8 per group). Rats in sham operation group and operation group received single subcutaneous injection of monocrotaline (MCT, 60 mg/kg). After four weeks, the mean pulmonary arterial pressure (mPAP) and other hemodynamic parameters were measured with the right heart catheter in rats of these two groups. Then, operation group received the surgery of TPADN, which included thoracotomy in left 2-3 rib, exposing pulmonary artery, and removing the near connective tissue of the pulmonary artery trunk. After two weeks of operation, the mPAP and other hemodynamic parameters were measured again by the right heart catheter. The microstructure changes of the heart and pulmonary vessels was observed by immunohistochemistry and immunofluorescence. Meanwhile, RV cardiomyocyte cross-sectional area (CSA) and the right hearthy pertrophy index (RVHI= RV/[LV+S]) were used to evaluate the degree of right ventricular hypertrophy. Results:After four weeks of injection of MCT, the mPAP was significantly higher in the operation group and the sham operation group than in control group (P＜0.01). Two weeks after the surgery of TPADN, the mPAP was significantly reduced in the operation group than compared in the sham group(P＜0.01). Meanwhile, the percentage of medial thickness to outer diameter of the small pulmonary arterioles, right ventricular myocardial cell cross-sectional area and RVHI were also significantly decreased in the operation group compared to sham operation group(all P＜0.01). Conclusions:Our results show that TPADN could reduce the mean pulmonary arterial pressure and attenuate the hypertrophy of medial thickness of small pulmonary arterioles and of right ventricle in PAH rats induced by monocrotaline.