Pardo, FabianFabianPardoNatalia Guajardo CelisJoaquín Araos HenríquezCarlos SanhuezaFernando ToledoA. BeltránAndrea LeivaMarco A. RamírezLuis Sobrevía2025-08-252025-08-252017-01-1710.1016/j.placenta.2017.01.1202-s2.0-85009921486https://cris-uv-2.scimago.es/handle/123456789/3064WOS:000398645400002Introduction Adenosine is taken up via human equilibrative nucleoside transporters 1 (hENT1) and 2 (hENT2) at a physiological extracellular pH (pHo ∼7.4) in human umbilical vein endothelial cells (HUVECs). Acidic pHo increases the uptake of adenosine and 5-hydroxytryptamine (5HT) via hENT4 in this cell type. However, modulation of hENT1 and hENT2 transport activity by the pHi is unknown. We investigated whether hENT1 and hENT2-adenosine transport was regulated by acidic pHi. Methods HUVECs loaded with a pH sensitive probe were subjected to 0.1–20 mmol/L NH4Cl pulse assay to generate 6.9–6.2 pHi. Before pHi started to recover, adenosine transport kinetics (0–500 μmol/L, 37 °C) in the absence or presence 1 or 10 μmol/L S-(4-nitrobenzyl)-6-thio-inosine (NBTI), 2 mmol/L hypoxanthine, 2 mmol/L adenine, 100 μmol/L 5HT, or 500 μmol/L adenosine, was measured. Results Overall adenosine transport (i.e., hENT1+hENT2) was semisaturable and partially inhibited by 1 μmol/L, but abolished by 10 μmol/L NBTI in cells non-treated or treated with NH4Cl. The initial velocity and non-saturable, lineal component for overall transport were increased after NH4Cl pulse. hENT1 and hENT2-mediated adenosine transport maximal capacity was increased by acidic pHi. hENT1 activity was more sensitive than hENT2 activity to acidic pHi. Discussion hENT1 and hENT2-adenosine transport is differentially regulated by acidic pHi in HUVECs. These findings are important in pathologies associated with pHi alterations such as gestational diabetes mellitus.enacceso abiertoDevelopmental BiologyObstetrics And GynecologyReproductive BiologyReproductive Medicinearticle