KCNN4 and pulmonary arterial hypertension: Regarding mRNA expression of KCa3.1 channels in animal models of pulmonary hypertension, previous results have been inhomogeneous: KCa3.1 mRNA expression have been found to be up-regulated in rats with monocrotaline-induced pulmonary hypertension [40] or unaltered in chronic hypoxic rats [39].