Hypoxanthine uptake by skeletal muscle microvascular endothelial cells from equilibrative nucleoside transporter 1 (ENT1)-null mice: Effect of oxidative stress

Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase tran...

Full description

Saved in:

Bibliographic Details
Published in:	Microvascular research Vol. 98; pp. 16 - 22
Main Authors:	Bone, D.B.J., Antic, M., Quinonez, D., Hammond, J.R.
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 01-03-2015
Subjects:	Adenosine Animals Catalase - metabolism Endothelial Cells - metabolism Endothelium Equilibrative Nucleoside Transporter 1 - genetics Equilibrative Nucleoside Transporter 1 - metabolism Female Free Radicals Hypoxanthine Hypoxanthine - chemistry Hypoxanthine - pharmacokinetics Ischemia Male Membrane Transport Proteins - metabolism Mice Mice, Inbred C57BL Mice, Knockout Microcirculation Muscle, Skeletal - cytology Nucleobase Nucleoside Oxidative Stress Oxygen - chemistry Reactive Oxygen Species - metabolism Reperfusion Injury Transporters Vasculature PBS Oxidative stress Adenosine MVEC ENBT1 ENT1 ENT2 NMG SOD ECGS ENT Nucleobase EDTA sI/R Vasculature Endothelium NBMPR TBHP Ischemia MnTMPyP ROS Transporters Hypoxanthine Nucleoside
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase transporter (ENBT1) which is involved in the cellular flux of adenosine metabolites such as hypoxanthine. Changes in either of these transport systems would impact the bioactivity of adenosine and its metabolism, including the formation of oxygen free radicals. MVEC isolated from skeletal muscle of ENT1+/+ and ENT1−/− mice were subjected to oxidative stress induced by simulated ischemia/reperfusion or menadione. The functional activities of ENT1 and ENBT1 were assessed based on zero-trans influx kinetics of radiolabeled substrates. There was a reduction in the rate of ENBT1-mediated hypoxanthine uptake by ENT1+/+ MVEC treated with menadione or after exposure to conditions that simulate ischemia/reperfusion. In both cases, the superoxide dismutase mimetic MnTMPyP attenuated the loss of ENBT1 activity, implicating superoxide radicals in the response. In contrast, MVEC isolated from ENT1−/− mice showed no reduction in ENBT1 activity upon treatment with menadione or simulated ischemia/reperfusion, but they did have a significantly higher level of catalase activity relative to ENT1+/+ MVEC. These data suggest that ENBT1 activity is decreased in MVEC in response to the increased superoxide radical that is associated with ischemia/reperfusion injury. MVEC isolated from ENT1−/− mice do not show this reduction in ENBT1, possibly due to increased catalase activity. •Simulated ischemia/reperfusion (sI/R) decreased hypoxanthine uptake by endothelial cells.•Loss of equilibrative nucleoside transport 1 (ENT1) leads to resistance to sI/R in ENT1−/− mice.•Catalase activity was increased in microvascular endothelial cells from ENT1−/− mice.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0026-2862 1095-9319
DOI:	10.1016/j.mvr.2014.11.005