Upregulating vascular endothelial KCa2.3 channels alleviates pulmonary hypertension in mice.

Endothelial dysfunction of pulmonary arteries is important in the initiation of pulmonary hypertension (PH). Pulmonary vascular tone is regulated by endothelium-dependent hyperpolarization (EDH) that induces vasodilation. Although K_Ca2.3 channels are involved as a key initiator of EDH response, therapeutic potential of endothelial K_Ca2.3 channels in PH remains unclear. Bioinformatic and biochemical analyses were used to explore K_Ca2.3 expression in patients with PH. Two mouse PH models were created by injection of Sugen 5416 plus hypoxia or injection with monocrotaline. Endothelial-specific K_Ca2.3 adeno-associated virus (AAV-Kcnn3) was constructed, and the efficacy in both PH models was tested using immunohistochemistry, myograph system, and echocardiography. Expression of K_Ca2.3 was decreased in pulmonary arterial endothelial cells or lung tissues from patients with PH and both experimental PH models. AAV-Kcnn3 treatment increased K_Ca2.3 expression in pulmonary endothelium and ameliorated K_Ca2.3-medieated vasodilation of small pulmonary arteries and pulmonary vascular endothelial dysfunction in both PH models. The key PH phenotypes, including elevated right ventricular pressure, Fulton index, pulmonary artery wall thickness, and the free wall thickness of the right ventricle, were remarkably alleviated by AAV-Kcnn3 treatment in both PH models. In conclusion, augmented expression of endothelium-specific K_Ca2.3 channels markedly inhibits the development of PH by improving endothelium-dependent relaxation. SIGNIFICANCE STATEMENT: This study demonstrated downregulated expression of K_Ca2.3 channels in lung tissues, specifically in pulmonary artery endothelial cells from patients or mice with pulmonary hypertension. Upregulation of endothelial K_Ca2.3 might serve as a therapeutic strategy in the early-stage pulmonary hypertension.