Abstract: To investigate the expression of calcium-sensing receptor (CaSR)  in pulmonary arterial smooth muscle  and hydrogen sulfide(H₂S)   in plasma of rats with high pulmonary blood flow  pulmonary hypertension (PH),and to clarify the role of both of them in the mechanism of PH.Methods 18 male SD rats were randomly divided into   control group and PH group.The left lung resection surgery was performed in rats in PH group.35 d after feeding,the right heart catheterization was used to measure mean pulmonary artery pressure(PAMP) of rats in  control group and PH group;the right ventricular weight / body weight (RV / BW) and right ventricle /(left ventricle + interventricular septum) ［RV/（LV+S)］ ratios were detected,and the changes of pulmonary vascular structure  were observed under  optical microscope.Spectrophotometry was used to detect the plasma H₂S content.Real-time quantitative PCR was performed to detect the CaSR mRNA expression in pulmonary artery endothelial cells of rats in tow groups.Results The PAMP,the RV/BW and RV/(LV+ S) ratios in PH group were significantly higher than those in control group (P<0.05).Under light microscope,the pulmonary vascular muscle level was increased and the lung relative medial thickness of middle and small muscular arteries was also increased significantly in PH group(P<0.05).The CaSR mRNA expression in pulmonary artery endothelial cells in PH group was significantly higher than that in control group (P<0.05);the plasma H₂S content in PH group was significantly decreased compared with control group(P<0.05).Conclusion The changes of the CaSR mRNA expression in pulmonary artery endothelial cells in high pulmonary blood flow condition may be involved in PH  by changing the generation of endogenous H₂S.
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Key words: calcium-sensing receptor, hydrogen sulfide, high pulmonary blood flow, pulmonary hypertension, smooth muscle