The Role of Na+/Ca2+ Exchanger 1 in Maintaining Ductus Arteriosus Patency

Patency of the ductus arteriosus (DA) is crucial for both fetal circulation and patients with DA-dependent congenital heart diseases (CHD). The Na⁺/Ca²⁺ exchanger 1 (NCX1) protein has been shown to play a key role in the regulation of vascular tone and is elevated in DA-dependent CHD. This current study was conducted to investigate the mechanisms underpinning the role of NCX1 in DA patency. Our data showed NCX1 expression was up-regulated in the DA of fetal mice. Up-regulation of NCX1 expression resulted in a concomitant decrease in cytosolic Ca²⁺ levels in human DA smooth muscle cells (DASMCs) and an inhibition of the proliferation and migration capacities of human DASMCs. Furthermore, treatment of DASMCs with KB-R7943, which can reduce Ca²⁺ influx, resulted in the inhibition of both cell proliferation and migration. These findings indicate that NCX1 may play a role in maintaining patent DA not only by preventing DA functional closure through reducing cytosolic Ca²⁺ level in DASMC but also by delaying the anatomical closure process. The latter delay is facilitated by the down-regulation of human DASMC proliferation and migration. It is also likely that a reduction in cytosolic Ca²⁺ levels inhibits the proliferation and migration capacities of human DASMCs in vitro.