Intracellular acidification reduces l-arginine transport via system y+L but not via system y+/CATs and nitric oxide synthase activity in human umbilical vein endothelial cells

Intracellular acidification reduces l-arginine transport via system y+L but not via system... l-Arginine is taken up via the cationic amino acid transporters (system y+/CATs) and system y+L in human umbilical vein endothelial cells (HUVECs). l-Arginine is the substrate for endothelial NO synthase (eNOS) which is activated by intracellular alkalization, but nothing is known regarding modulation of system y+/CATs and system y+L activity, and eNOS activity by the pHi in HUVECs. We studied whether an acidic pHi modulates l-arginine transport and eNOS activity in HUVECs. Cells loaded with a pH-sensitive probe were subjected to 0.1–20 mmol/L NH4Cl pulse assay to generate pHi 7.13–6.55. Before pHi started to recover, l-arginine transport (0–20 or 0–1000 μmol/L, 10 s, 37 °C) in the absence or presence of 200 μmol/L N-ethylmaleimide (NEM) (system y+/CATs inhibitor) or 2 mmol/L l-leucine (systemy+L substrate) was measured. Protein abundance for eNOS and serine1177 or threonine495 phosphorylated eNOS was determined. The results show that intracellular acidification reduced system y+L but not system y+/CATs mediated l-arginine maximal transport capacity due to reduced maximal velocity. Acidic pHi reduced NO synthesis and eNOS serine1177 phosphorylation. Thus, system y+L activity is downregulated by an acidic pHi, a phenomenon that may result in reduced NO synthesis in HUVECs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease Elsevier

Intracellular acidification reduces l-arginine transport via system y+L but not via system y+/CATs and nitric oxide synthase activity in human umbilical vein endothelial cells

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Publisher
Elsevier
Copyright
Copyright © 2018 Elsevier B.V.
ISSN
0925-4439
D.O.I.
10.1016/j.bbadis.2018.01.032
Publisher site
See Article on Publisher Site

Abstract

l-Arginine is taken up via the cationic amino acid transporters (system y+/CATs) and system y+L in human umbilical vein endothelial cells (HUVECs). l-Arginine is the substrate for endothelial NO synthase (eNOS) which is activated by intracellular alkalization, but nothing is known regarding modulation of system y+/CATs and system y+L activity, and eNOS activity by the pHi in HUVECs. We studied whether an acidic pHi modulates l-arginine transport and eNOS activity in HUVECs. Cells loaded with a pH-sensitive probe were subjected to 0.1–20 mmol/L NH4Cl pulse assay to generate pHi 7.13–6.55. Before pHi started to recover, l-arginine transport (0–20 or 0–1000 μmol/L, 10 s, 37 °C) in the absence or presence of 200 μmol/L N-ethylmaleimide (NEM) (system y+/CATs inhibitor) or 2 mmol/L l-leucine (systemy+L substrate) was measured. Protein abundance for eNOS and serine1177 or threonine495 phosphorylated eNOS was determined. The results show that intracellular acidification reduced system y+L but not system y+/CATs mediated l-arginine maximal transport capacity due to reduced maximal velocity. Acidic pHi reduced NO synthesis and eNOS serine1177 phosphorylation. Thus, system y+L activity is downregulated by an acidic pHi, a phenomenon that may result in reduced NO synthesis in HUVECs.

Journal

Biochimica et Biophysica Acta (BBA) - Molecular Basis of DiseaseElsevier

Published: Apr 1, 2018

References

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