TRPV1 and pulmonary arterial hypertension: The increased [Ca2+]i in PAH PASMCs comes from the influx of calcium through the above three types of channels in cytomembranes, including TRPV1 absolutely, and the efflux of calcium from the ER through ryanodine receptor (RyR) channels and inositol triphosphate receptors (IP3R) channels in the ER membrane [27].