Chemico-Biological Interactions 182 (2009) 199–203
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Dual action of phenylarsine oxide on the glucose transport activity of GLUT1
Jordan Scott, Adeleye Opejin, Andrew Tidball, Nathan Stehouwer, Janelle Rekman, Larry L. Louters
Department of Chemistry and Biochemistry, Calvin College, Grand Rapids, MI 49546, USA
Received 1 June 2009
Received in revised form 24 July 2009
Accepted 9 August 2009
Available online 15 August 2009
L929 ﬁbroblast cells
An early event in the toxic effects of organic arsenic compounds, such as phenylarsine oxide (PAO), is
an inhibition of glucose uptake. Glucose uptake involving the glucose transporter, GLUT4 is inhibited by
PAO indicating an importance of vicinal sulfhydryls in insulin-stimulated glucose uptake. However, the
data on effects of PAO on GLUT1 are conﬂicting. This study investigated the effects of PAO on glucose
uptake in L929 ﬁbroblast cells, cells, which express only GLUT1. The data presented here reveal a dual
effect of PAO. At low concentrations or short exposure times PAO stimulated glucose uptake reaching a
peak activation of about 400% at 3 M. At higher concentrations (40 M), PAO clearly inhibited glucose
uptake. At intermediate concentrations (10 M), PAO had no effect under basal conditions but completely
inhibited activation of glucose uptake by glucose deprivation and partially inhibited methylene blue-
stimulated glucose uptake. PAO increased the speciﬁc binding of cytochalasin B to GLUT1 suggesting a
direct interaction with the transporter. These data are most consistent with PAO interacting with multiple
proteins that regulate the activity of this transporter, one of which may be GLUT1 itself. The identity of
these proteins will require further investigation.
© 2009 Elsevier Ireland Ltd. All rights reserved.
Phenylarsine oxide (PAO) is a trivalent arsenic compound that
forms cyclic thioarsenite complexes with vicinal sulfhydryls. It has
been extensively used as a tool for detecting and blocking thiol
dependent biological processes. In particular PAO has been used
to probe membrane receptor or transport mediated events such
as glucose uptake. It has been demonstrated that PAO inhibits
insulin-stimulated glucose uptake in adipocytes [1–5] and hepa-
tocytes , as well as inhibiting both insulin-stimulated glucose
and amino acid uptake in muscle [7–9]. This effect may be a func-
tion of inhibition of GLUT4 translocation  and/or stimulation of
GLUT4 degradation . PAO also inhibits binding of insulin to its
receptor  as well as the feedback inhibitory effects of insulin
and IGF-1 on insulin release .
The effects of PAO on glucose uptake under basal or non-insulin-
stimulating conditions are less clear. PAO has been reported to
inhibit basal glucose uptake in kidney cells [13,14], adipocytes 
and endothelial cells . Indeed, the inhibition of glucose uptake
appears to be a very early event in the pathogenesis of organic
arsenical toxicity [13,14]. Notably, however, some investigators
report that PAO either has no effect under basal conditions [2,8],
Abbreviations: PAO, phenylarsine oxide; DMSA, meso-2,3-dimercaptosuccinic
acid; MB, methylene blue.
Corresponding author. Tel.: +1 616 526 6493; fax: +1 616 526 8551.
E-mail address: firstname.lastname@example.org (L.L. Louters).
or that it activates glucose uptake [7,16]. These conﬂicting data can
be attributed, in part, to differential effects of PAO on GLUT4 ver-
sus GLUT1. PAO has been shown to inhibit cytochalasin B binding
in insulin-sensitive adipoctyes suggesting that it directly binds to
GLUT4 . A trivalent arsenical afﬁnity column complexes with
GLUT4, but not with GLUT1 . Also, PAO is reported to have
no effect on transport in erythrocytes or vesicles, which contain
only GLUT1 [19,20]. However, there is also evidence that PAO does
affect the transport activity of GLUT1 as well as GLUT4. It has been
previously reported that PAO can inhibit the acute activation of glu-
cose uptake in L929 ﬁbroblast cells, cells that contain only GLUT1
. The activation of glucose uptake by either methylene blue, a
redox dye, or by glucose deprivation was completely blocked by
PAO [22,23]. The effects of PAO at basal conditions in these studies
were mixed, reporting both an inhibition  and an activation of
glucose uptake .
The purpose of this study was to make a careful systematic study
of the effects of PAO on GLUT1 mediated glucose uptake, under
both basal and activating conditions in order to clarify the effects of
PAO and the potential importance of vicinal thiols in the transport
activity of GLUT1.
2. Materials and methods
Phenylarsine oxide (PAO), meso-2,3-dimercaptosuccinic acid
0009-2797/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved.