Change of endogenous hydrogen sulfide pathway in the monocrotaline-induced pulmonary hypertensive rats

Abstract

Objective To investigate the production of hydrogen sulfide (H2S) in rats with monocrotaline (MCT)-induced pulmonary hypertension(PAH). Methods Fourteen male Wistar rats were randomly divided into 2 groups (7 cases for each group): control group and MCT group.Rats in the MCT group were intraperitoneally injected with MCT (60 mg/kg) on day 1 while rats in the control group received only the same volume of 9 g/L saline.And then the conventional breeding was given for 21 days.Mean pulmonary artery pressure (mPAP) was evaluated via right cardiac catheterization procedure.The ratio of right ventricular mass (RV) and left ventricular plus septal mass (LV+ SP)[RV/(LV+ SP)] was calculated.The morphological change of pulmonary artery was observed by applying hematoxylin-eosin (HE) staining on the lung tissue paraffin section by measuring relative media thickness (RMT) and relative media area (RMA) of pulmonary aetery.H2S contents in serum and lung tissue rat were detected by using free radicals detector.The expression of cystathionine-γ-lyase (CSE), a key enzyme catalyzing endogenous H2S generaion, in lung tissue was detected by using Western blot method.CSE mRNA level in lung was detected by adopting the real-time polymerase chain reaction (RT-PCR) method. Results Compared with control group, mPAP of rats in MCT group was increased significantly [(49.31±3.67) mmHg vs (14.31±2.07) mmHg(1 mm Hg=0.133 kPa), P<0.01] and the ratio of RV/(LV+ SP) was increased (0.43±0.03 vs 0.21±0.03, P<0.01), while RMT and RMA of pulmonary artery were enlarged [(43.46±1.94) μm vs (13.16±1.48) μm, P<0.01; (3 321.10±318.20) μm2vs (963.40±127.26) μm2, P<0.01]. The evaluation of microstructure of pulmonary artery showed that the vessel wall of pulmonary artery in control rats was thin and no inflammatory cell was observed around artery.However, the vessel wall of pulmonary artery in rats of MCT group was thickened and there was evident infiltration of inflammatory cells in perivascular area.Compared with control group, H2S contents in serum and lung tissue of rats in MCT group were markedly decreased[ (9.28±0.94) μmol/L vs (14.20±1.21) μmol/L, P<0.01; (0.43±0.08) μmol/g protein vs (0.87±0.17) μmol/g protein, P<0.01], while CSE protein and mRNA expression in lung tissue of rats in MCT group were downregulated (0.14±0.02 vs 0.28±0.09, P<0.01; 0.84±0.06 vs 1.12±0.04, P<0.01). Conclusion Endogenous H2S pathway is significantly downregulated in rats with monocrotaline-induced pulmonary hypertension. Key words: Pulmonary arterial hypertension; Monocrotaline; Hydrogen sulfide