KCNA5 and pulmonary arterial hypertension: The concentration of cytosolic calcium ion in PASMC is closely associated with the cellular function, and previous researches reported that the concentration of cytosolic calcium ion in PASMC from patients with PAH was significantly increased, which was partly mediated by activation of transient receptor potential channel (TrpC)6 and downregulation of voltage gated potassium channels like Kv1.5 (2, 30, 31).