Sodium-coupled neutral amino acid transporter 1 (SNAT1) modulates L-citrulline transport and nitric oxide (NO) signaling in piglet pulmonary arterial endothelial cells

• Published in: PloS one Vol. 9; no. 1; p. e85730
• Main Authors: Dikalova, Anna, Fagiana, Angela, Aschner, Judy L, Aschner, Michael, Summar, Marshall, Fike, Candice D
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 2014; Public Library of Science (PLoS)
• Subjects: Acids; Amino Acid Transport System A - physiology; Amino acids; Animals; Arginine; Biological Transport; Biology; Cell Hypoxia; Cells, Cultured; Children & youth; Citrulline; Citrulline - metabolism; Coupling; Endothelial cells; Endothelial Cells - metabolism; Endothelium, Vascular - pathology; Heart attacks; Hypertension; Hypertension, Pulmonary - metabolism; Hypoxia; L-citrulline; Laboratory animals; Lung diseases; Medicine; Metabolism; Monomers; Nitric oxide; Nitric Oxide - metabolism; Nitric Oxide Synthase Type III - metabolism; Pediatrics; Polyamines; Proteins; Pulmonary arteries; Pulmonary Artery - pathology; Pulmonary hypertension; Ribonucleic acid; RNA; RNA-mediated interference; Rodents; Signal Transduction; Signaling; siRNA; Sodium; Superoxides - metabolism; Sus scrofa; Transport; Vascular diseases; Veins & arteries; New York; United States > US; Tennessee; Nashville Tennessee
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0085730

There is evidence that impairments in nitric oxide (NO) signaling contribute to chronic hypoxia-induced pulmonary hypertension. The L-arginine-NO precursor, L-citrulline, has been shown to ameliorate pulmonary hypertension. Sodium-coupled neutral amino acid transporters (SNATs) are involved in the transport of L-citrulline into pulmonary arterial endothelial cells (PAECs). The functional link between the SNATs, L-citrulline, and NO signaling has not yet been explored. We tested the hypothesis that changes in SNAT1 expression and transport function regulate NO production by modulating eNOS coupling in newborn piglet PAECs. A silencing RNA (siRNA) technique was used to assess the contribution of SNAT1 to NO production and eNOS coupling (eNOS dimer-to-monomer ratios) in PAECs from newborn piglets cultured under normoxic and hypoxic conditions in the presence and absence of L-citrulline. SNAT1 siRNA reduced basal NO production in normoxic PAECs and prevented L-citrulline-induced elevations in NO production in both normoxic and hypoxic PAECs. SNAT1 siRNA reduced basal eNOS dimer-to-monomer ratios in normoxic PAECs and prevented L-citrulline-induced increases in eNOS dimer-to-monomer ratios in hypoxic PAECs. SNAT1 mediated L-citrulline transport modulates eNOS coupling and thus regulates NO production in hypoxic PAECs from newborn piglets. Strategies that increase SNAT1-mediated transport and supply of L-citrulline may serve as novel therapeutic approaches to enhance NO production in patients with pulmonary vascular disease.