T-type voltage gated calcium channels are involved in endothelium-dependent relaxation of mice pulmonary artery

Abstract

In pulmonary arterial endothelial cells, Ca²⁺ channels and intracellular Ca²⁺ concentration ([Ca²⁺]_i) control the release of vasorelaxant factors such as nitric oxide and are involved in the regulation of pulmonary arterial blood pressure. The present study was undertaken to investigate the implication of T-type voltage-gated Ca²⁺ channels (T-VGCCs, Ca_v3.1 channel) in the endothelium-dependent relaxation of intrapulmonary arteries. Relaxation was quantified by means of a myograph in wild type and Ca_v3.1^-/- mice. Endothelial [Ca²⁺]_i and NO production were measured, on whole vessels, with the fluo-4 and DAF-fm probes. Acetylcholine (ACh) induced a nitric oxide- and endothelium-dependent relaxation that was significantly reduced in pulmonary arteries from Ca_v3.1^-/- compared to wild type mice as well as in the presence of T-VGCC inhibitors (NNC 55-0396 or mibefradil). ACh also increased endothelial [Ca²⁺]_i and NO production that were both reduced in Ca_v3.1^-/- compared to wild type mice or in the presence of T-VGCC inhibitors. Immunofluorescence labeling revealed the presence of Ca_v3.1 channels in endothelial cells that co-localized with endothelial nitric oxide synthase in arteries from wild type mice. TRPV4-, beta2 adrenergic- and nitric oxide donors (SNP)-mediated relaxation were not altered in Ca_v3.1^-/- compared to wild type mice. Finally, in chronically hypoxic mice, a model of pulmonary hypertension, ACh relaxation was reduced but still depended on Ca_v3.1 channels activity. The present study thus demonstrates that T-VGCCs, mainly Ca_v3.1 channel, contribute to intrapulmonary vascular reactivity in mice by controlling endothelial [Ca²⁺]_i and ACh-mediated relaxation.

Keywords: Acetylcholine PubChem CID: 6060; Calcium channel; Endothelium; GSK1016790A PubChem CID: 23630211; Mibefradil PubChem CID: 60662; NNC55-0396 PubChem CID: 71311835; Nicardipine PubChem CID: 41114; PGF2α PubChem CID: 5280363; Phenylephrine PubChem CID: 5284443; Pulmonary artery; Relaxation; T-type; l-NAME PubChem CID: 135193.