The proliferation rates of PASMCs from normal subjects, IPAH patients, and CTEPH patients were analyzed using quantitative colorimetric assay based on the BrdU incorporation method for cell proliferation. The effects of NPS2143 (A), Calhex 231 (B), and R568 (C) on cell proliferation were examined in normal, IPAH, and CTEPH PASMCs. Summarized data (a) show the effect of CaSR modulators at a concentration of 3 μM on cell proliferation at 48 (for R568) or 72 (for NPS2143 and Calhex 231) h in normal, IPAH, and CTEPH PASMCs. Dose-response curve (b) of cell proliferation for NPS2143, Calhex 231, and R568 in IPAH-PASMCs. The absorbance was normalized by the value in the absence of drug (as 100%). The IC50 values of NPS2143 and Calhex 231 for the proliferation of IPAH-PASMCs were 1.48 and 0.62 μM, respectively. The EC50 value of R568 was 0.34 μM. Data were obtained from 7~14 experiments. *p<0.05 or **p<0.01 vs. control (100%).