Nuclear Medicine and Biology 84–85 (2020) 33–37

Contents lists available at ScienceDirect

Nuclear Medicine and Biology
journal homepage: www.elsevier.com/locate/nucmedbio

Transport mechanism and afﬁnity of [99mTc]Tc-mercaptoacetyltriglycine([99mTc]MAG3) on the apical membrane of renal proximal tubule cells
Masato Kobayashi a,⁎, Kodai Nishi b, Asuka Mizutani a, Hiroyuki Okudaira c, Takeo Nakanishi d, Naoto Shikano e,
Ryuichi Nishii f, Ikumi Tamai g, Keiichi Kawai a,haSchool of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Ishikawa, Japan
Department of Radioisotope Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japanc
Research and Business Development Department, Nihon Medi-Physics Co., Ltd., Tokyo, JapandFaculty of Pharmacy, Takasaki University of Health and Welfare, Gunma, Japane
Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japanf
Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, Chiba, Japang
School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Ishikawa, Japanh
Biomedical Imaging Research Center, University of Fukui, Fukui, Japanba r t i c l e

i n f oArticle history:
Received 7 November 2019
Received in revised form 26 December 2019
Accepted 14 January 2020
Keywords:[99mTc]MAG3
Single photon emission computed tomography
imaging
Renal scintigraphy
Renal proximal tubule cells
Adenosine triphosphate-binding cassettetransportersa b s t r a c t
Technetium-99m-labeled mercaptoacetyltriglycine ([99mTc]MAG3) is widely used for evaluation of transplanted
kidneys, diagnosis of tubular necrosis, and scintigraphic studies of tubular function. [99mTc]MAG3 is a substrate
for organic anion transporter (OAT)1 and OAT3 on the basolateral membrane side for renal secretion. We investigated the transport mechanism and afﬁnity of [99mTc]MAG3 on the apical membrane of renal proximal tubule
cells for renal secretion. Adenosine triphosphate-binding cassette (ABC) transporters for renal secretion of[ 99mTc]MAG3 were examined using ABC transporter vesicles expressing multiple drug resistance 1 (MDR1),
breast cancer resistance protein (BCRP), multidrug resistance-associated protein (MRP)2, and MRP4. MK-571,
a MRP inhibitor, was applied to measure the Km and Vmax of MRP2 and MRP4 in a vesicle transport assay. Single
photon emission computed tomography (SPECT) was performed in normal rats and MRP2-deﬁcient Eisai
hyperbilirubinuria rats (EHBR) using [99mTc]MAG3 with and without MK-571. [99mTc]MAG3 uptake in adenosine
triphosphate was signiﬁcantly higher than that in adenosine monophosphate in vesicles that highly expressed
MRP2 and MRP4. The afﬁnity of [ 99mTc]MAG3 for MRP4 was higher than that for MRP2. Renal secretion via
MRP2 and MRP4 was identiﬁed by comparing normal and EHBR rats with and without MK-571 on SPECT.
[99mTc]MAG3 is transported via MRP2 and MRP4 on the apical membrane of renal proximal tubule cells. The afﬁnity of MRP4 is higher than that of MRP2.
Signiﬁcance statement: [99mTc]MAG3, widely used for evaluation of transplanted kidneys, diagnosis of tubular necrosis, and scintigraphic studies of tubular function, is transported via MRP2 and MRP4 on the apical membraneof renal proximal tubule cells. The afﬁnity of MRP4 is higher than that of MRP2.
© 2020 Elsevier Inc. All rights reserved.

1. Introduction
Urinary excretion of drugs is determined by glomerular ﬁltration, tubular secretion, and reabsorption from the urine. In renal scintigraphy,

Abbreviations: [99mTc]MAG3, technetium-99 m-labeled mercaptoacetyltriglycine;
OAT, organic anion transporter; ATP, adenosine triphosphate; ABC, adenosine
triphosphate-binding cassette; MDR1, multidrug resistance protein 1; BCRP, breast cancer
resistance protein; MRP2, multidrug resistance-associated protein 2; MRP4, multidrug
resistance-associated protein 4; SPECT, single photon emission computed tomography;
PET, positron emission tomography; CT, computed tomography; AMP, adenosine
monophosphate; EHBR, Eisai hyperbilirubinuria rat.
⁎ Corresponding author at: School of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa 920-0942,
Japan.
E-mail address: kobayasi@mhs.mp.kanazawa-u.ac.jp (M. Kobayashi).
https://doi.org/10.1016/j.nucmedbio.2020.01.002
0969-8051/© 2020 Elsevier Inc. All rights reserved.

technetium-99m-labeled mercaptoacetyltriglycine ([ 99mTc]MAG3) iswidely used for evaluation of transplanted kidneys, diagnosis of tubular
necrosis, and scintigraphic studies of tubular function [1]. [99mTc]MAG3
is a substrate for organic anion transporter (OAT) 1 in cDNA-transfected
cells, suggesting that OAT1 accounts for the kidney uptake of [ 99mTc]
MAG3 on the basolateral membrane side from blood for renal secretion[2]. In renal proximal tubule cells, not only OAT1 but also OAT3 and organic cation transporter 2 are mainly expressed on the basolateral
membrane; these transporters are classiﬁed as solute carrier transporters [4]. The transport activity of [ 99mTc]MAG3 in OAT1-expressing
cells is higher than in OAT3-expressing cells [3].
On the other hand, ATP-binding cassette (ABC) transporters aremainly located on the apical membrane of renal proximal tubule cells
and include multidrug resistance protein 1 (MDR1), breast cancer resistance protein (BCRP), multidrug resistance-associated protein (MRP) 2,

34

M. Kobayashi et al. / Nuclear Medicine and Biology 84–85 (2020) 33–37

MRP4 [4,5]. Among these ABC transporters, MDR1, BCRP, MRP2, and
MRP4 are likely to be involved in efﬂux of organic anion drugs such as[ 99mTc]MAG3 (Fig. 1). However, the transport mechanism and afﬁnityof [ 99mTc]MAG3 on the apical membrane of renal proximal tubule
cells are unknown. In this study, we investigated the transport mechanism and afﬁnity of [ 99mTc]MAG3 on the apical membrane in renal
secretion.
2. Materials and methods
2.1. Materials[ 99mTc]MAG3 was purchased from Nihon Medi-Physics Co., Ltd.
(Chiba, Japan). MK-571 sodium salt was purchased from Cayman
Chemical (Ann Arbor, MI, USA).

gamma counter (AccuFLEXγ7000, Aloka, Tokyo, Japan). Uptake of[ 99mTc]MAG3 in ATP solution was compared with that in AMP. For analyzing afﬁnity of MRP2 and MRP4, MK-571 (1.0, 1.3, 1.5, 2.0, 2.5, 5.0, 7.5,
10, 25, 50, 100 μM), a MRP inhibitor, was added in the transport assay
with vesicles to measure the Km and Vmax using Michaelis–Menten
model. At the end of the incubation, each well was rapidly washedtwice with 1 ml ice-cold buffer (100 μM HEPES-Tris, 1 mM KNO3,
0.5 mM sucrose). The radioactivity of each sample was measured
using the gamma counter. The vesicles were then solubilized in 0.5 ml
0.1 N NaOH, and the protein concentration was measured using a BCA
Protein Assay Kit (Thermo Fisher Scientiﬁc, Kanagawa, Japan). All samples were examined in quadruplicate.

2.4. Planar imaging and biological distribution of [ 99mTc]MAG3 in normal
rats and EHBR rats with and without MK-571 loading

2.2. Vesicles
To investigate ABC transporters, we used vesicles (GenoMembrane
Inc., Kanagawa, Japan) with high expression of human MDR1, MRP2,
MRP4, or BCRP. Experimental kits were also purchased from
GenoMembrane Inc. and were used for experiments for each ABC
transporter.
2.3. Transport assays with vesicles overexpressing ABC transporters
Transport via ABC transporters was measured using vesicles overexpressing MDR1, MRP2, MRP4, or BCRP. These vesicles were preincubated for 10 min in reaction buffer (10 mM HEPES-Tris, 100 mM
KNO3, 10 mM Mg(NO3)2, 50 mM sucrose). [ 99mTc]MAG3 (37 kBq) was
incubated with each vesicle solution for 5 min with ATP or adenosine
monophosphate (AMP), and radioactivity was measured using a

Secretion

Apicalmembrane

Basolateral
membrane

MDR1

OAT1
BCRP

Blood

Ureter
MRP2

OAT3

MRP4

Urine
Reabsorption
Fig. 1. Transport systems for organic anion drugs in the epithelial cells of renal proximal
tubule cells. For secretion of [99mTc]MAG3, the transport system includes the organic
anion transporter (OAT)1 and OAT3 on the basolateral membrane and multidrug
resistance protein 1 (MDR1), breast cancer resistance protein (BCRP), multidrug
resistance-associated protein (MRP)2, and MRP4 on the apical membrane.

Our research adhered to the Principles of Laboratory Animal Care
(NIH publication #85-23, revised in 1985). All animal studies werealso conducted following approval by the Animal Care Committee of Kanazawa University and Nagasaki University (AP-122340). For planar
imaging, normal rats (Sprague Dawley, male, 6 weeks old, n = 4) andEisai hyperbilirubinuria (EHBR) rats (male, 6 weeks old, n = 8) werehoused under a 12-hour light/12-hour dark cycle with free access towater and food and then to only water for one night before the day ofthe experiment. Planar imaging with a single pinhole collimator was
immediately started with an intravenous bolus administration of[ 99mTc]MAG3 (about 70 MBq) using a micro-injection pump
(CFX1010, ISIS, Osaka, Japan) for 15–20 s into the tail vein of normal
rats (n = 4) under 2.0–2.5% isoﬂurane (Abbott Laboratories, Green
Oaks, IL, USA). Imaging continued for about 30 min (20 s/frame for5 min, 30 s/frame for 5 min, and 300 s/frame for 20 min) using a small
animal single photon emission computed tomography/positron emission tomography/computed tomography (SPECT/PET/CT) imaging
scanner (TriFoil Imaging, Inc., Northridge, CA, USA). The data were reconstructed using maximum likelihood-expectation maximization
with six iterations including attenuation and no scatter correction. The
voxel size was set to 0.53 × 0.53 × 0.37 mm. Post-reconstructionsmoothing ﬁltering was applied using a 1.0-mm Gaussian ﬁlter. Image
displays were obtained using Amide's a medical image data examiner,
which is an open-source medical image data analysis software tool(ver. 1.04). In these images, three to ﬁve regions of interest were placed
over the kidney, bladder and background radioactivity in blood, andthen the each time activity curve was obtained. The background of radioactivity in blood was subtracted from the radioactivity of kidney
and bladder. We determined average time-to-peak (Tmax) and averagetimes to half-maximal activity (T1/2) and area under the curve (AUC).
EHBR rats (n = 4 of 8) were imaged to evaluate the effect of MRP2
using the same protocol of SPECT/CT imaging that was used for normal
rats. After radioactive decay of 99mTc in the above mentioned EHBR rats,
the same EHBR rats were used for evaluation of the effect of 1.0 mM MK571, a MRP inhibitor. The EHBR rats were injected with a mixture of[ 99mTc]MAG3 and MK-571, and planar imaging was immediately acquired using the same imaging protocol that was used for normal rats.
For biological distribution studies, normal SD rats (male, 6 weeks
old, n = 4), EHBR rats (male, 6 weeks old, n = 8) were housed with a
12-h light/12-h dark cycle with free access to only water. Normal rats
and EHBR rats (n = 4) that had fasted all night were administered[ 99mTc]MAG3 via the tail vein (3.7 MBq/rat). At 5, 10, and 30 min, normal rats were euthanized under isoﬂurane anesthesia, and the following tissues were collected: blood, liver, kidney, bladder, and muscle.
Tissues were weighed, and radioactivity was quantiﬁed using a γ-ray
counter to calculate the percent injected dose (radioactive cpm in tissue
sample divided by cpm of injected radioactivity per gram of tissue × 100(%ID/g)). For the MK-571 inhibition study, the EHBR rats (n = 4) were
injected with a mixture of [ 99mTc]MAG3 and MK-571, and theM. Kobayashi et al. / Nuclear Medicine and Biology 84–85 (2020) 33–37

35

distribution studies were performed using the same protocol that wasused for normal and EHBR rats.
2.5. Statistical analysis
Data are presented as the means and standard deviations. P values
were calculated using the two-tailed paired Student's t-test for comparison between two groups and repeated-measures analysis of variancefor comparison among three groups. Statistical analyses were performed with Graphpad Prism 8 software (San Diego, CA, USA). A P
value b .05 was considered signiﬁcant.
3. Results
Fig. 2 shows uptake of [ 99mTc]MAG3 by vesicles overexpressing ABC
transporters. [ 99mTc]MAG3 uptake into vesicles that highly expressed
MRP2 or MRP4 in the presence of ATP was signiﬁcantly higher thanthat in the presence of AMP (P b .01), but not MDR1 and BCRP. Uptake
by MRP4 was higher than that by MRP2. Fig. 3 shows determination of
the Km and Vmax using MK-571 in the vesicle transport assay. The Km
values of MK-571 for MRP2- and MRP4-mediated [ 99mTc]MAG3 uptake
were 8.1 ± 1.2 μM (R2 = 0.98) and 4.5 ± 1.0 μM (R2 = 0.94), respectively. The Vmax values for MRP2- and MRP4-mediated [ 99mTc]MAG3
uptake were 13.3 ± 0.6 μM (R 2 = 0.98) and 12.8 ± 0.8 μM (R 2 =0.94), respectively.
Next, we obtained SPECT images and time activity curves with rats
(normal or EHBR) injected with [ 99mTc]MAG3 with or without MK571 loading (Fig. 4). The time activity curves of [ 99mTc]MAG3 derived
from SPECT images revealed the Tmax of 4.1 ± 1.2 min, 4.0 ± 1.5 min,and 6.5 ± 1.3 min in normal rats, EHBR rats, and EHBR rats with MK571 loading, respectively. The T1/2 were 8.8 ± 2.1 min, 17.4 ± 3.6 min,and 20.1 ± 3.8 min in normal rats, EHBR rats, and EHBR rats with MK571 loading, respectively. The AUC were 2.94 ± 0.61 cps × min,3.46 ± 0.59 cps × min, and 3.49 ± 0.83 cps × min in normal rats,
EHBR rats, and EHBR rats with MK-571 loading, respectively. RegardingµFig. 3. Measurement of Km and Vmax using MK-571 (1.0, 1.3, 1.5, 2.0, 2.5, 5.0, 7.5, 10, 25, 50,
100 μM) in the transport assay with vesicles overexpressing MRP2 (Δ and dotted line) and
MRP4 (● and solid line).

bladder accumulation of [99mTc]MAG3, normal rats showed the highest
accumulation immediately after administration, followed by EHBR rats
and then EHBR rats with MK-571 loading. In Table 1, radioactivity ofkidney and bladder in all rat groups were similar with time activity
curves derived from SPECT images in Fig. 4b and c. There was little difference in all rat groups in liver and muscle. EHBR rats with MK-571 inhibitor yielded higher radioactivity in blood than normal and EHBR rats.
4. Discussion
Anion drugs are usually transported by OATs, which are solute carrier transporters, and MRPs, which are ABC transporters [4]. [ 99mTc]
MAG3, an organic anion drug, is transported across the renal basolateral
membrane via OAT1 [2] and OAT3 [3], but the transport mechanism and

a

b

0.8
0.6

Uptake (nmol/mg protein)

0.8

ATP
AMP

0.6

0.4

0.4

0.2

0.2

0.0

0.0
0

1

2

3

4

5

0

c

d

10.0

10.0

1

2

3

4

5

*
*

8.0

8.0

6.0

6.0

*
4.0

*

*

2.0

*

4.0
2.0
0.0

0.0
0

1

2

3

4

5

0

1

2

3

4

5

Time (min)Fig. 2. Uptake of [99mTc]MAG3 by vesicles overexpressing each ABC transporter in ATP solution (● and solid line) and AMP solution (○ and dotted line) after 1, 3, and 5 min of incubation.
*P b .01 between uptake in ATP and AMP solution (n = 5; paired t-test). a; MDR1, b; BCRP, c; MRP2 and d; MRP4.

36

M. Kobayashi et al. / Nuclear Medicine and Biology 84–85 (2020) 33–37

aTable 1
Biological distribution of [99mTc]MAG3 on control, EHBR rats and EHBR rats with MK-571
loading.
Rats

Normal rats

EHBR rats

EHBR rats with
MK-571inhibitorb

0.3

Radioactivity (cps)Normal rats††††

EHBR rats

****

† ††

EHBR rats with MK-571 inhibitor†**** †
**

0.2

0.1

0.0
0

5

10

15

20

25

30

Time (min)cNormal rats
EHBR rats
EHBR rats with MK-571 inhibitor
1.2

Radioactivity (cps)

1.0
0.8
0.6
‡‡
‡‡‡‡
‡‡‡‡
‡‡
‡‡ †† ††‡‡ ††††
††
‡ ‡††
†† ††

0.4
0.2
0.0
0

****
** ** ******** **
****
5
10

‡‡
††

**

15

‡‡
††

**

20

‡‡
††

‡‡
††

**

**

25

30

Time (min)Fig. 4. SPECT images between 9 min and 10 min (a) and time activity curves in kidney(b) and bladder (c) of [99mTc]MAG3 in normal rats (●), EHBR rats (Δ), and EHBR rats
with MK-571 loading (■) under 2.0% isoﬂurane anesthesia injected with about 70 MBq[99mTc]MAG3 for 30 min. ‡P b .01 and ‡‡P b .05 for radioactivity between normal rats and
EHBR rats, ⁎P b .01 and ⁎⁎P b .05 for radioactivity between normal rats and EHBR rats
with MK-571 loading, and †P b .01 and ††P b .05 for radioactivity between EHBR rats and
EHBR rats with MK-571 loading (n = 4 in each group; repeated-measures analysis ofvariance).

the afﬁnity for drug transporters on the apical membrane of renal proximal tubule cells were unknown. In this study, we showed that [99mTc]
MAG3 was transported by MRP2 and MRP4 on the apical membrane ofrenal proximal tubule cells (Figs. 1 and 2). Fig. 3 showed that the afﬁnity

Organ(%ID/g)5 min

10 min30 minBlood
Liver
KidneyBladder
MuscleBlood
Liver
KidneyBladder
MuscleBlood
Liver
KidneyBladder
Muscle0.52 ± 0.14
0.11 ± 0.03
13.43 ± 2.91
20.89 ± 5.11
0.18 ± 0.05
0.57 ± 0.18
0.13 ± 0.05
13.11 ± 3.51
17.44 ± 4.45
0.15 ± 0.05
0.99††,⁎ ± 0.37
0.16 ± 0.08
9.61 ± 4.81
7.67††,⁎⁎ ± 3.13
0.18 ± 0.08

0.42 ± 0.11
0.28 ± 0.08
6.45 ± 1.12
41.34 ± 5.67
0.14 ± 0.03
0.45 ± 0.15
0.31 ± 0.10
7.25 ± 2.01
21.33†† ± 5.09
0.13 ± 0.04
0.75††,⁎ ± 0.22
0.34 ± 0.14
12.45† ± 3.44
15.84††,⁎ ± 4.33
0.17 ± 0.05

0.31 ± 0.09
0.35 ± 0.10
3.87 ± 0.95
56.78 ± 6.23
0.13 ± 0.04
0.33 ± 0.12
0.36 ± 0.12
4.93† ± 1.03
33.55†† ± 4.91
0.12 ± 0.05
0.39 ± 0.13
0.45† ± 0.14
3.42 ± 1.01
27.64††,⁎ ± 5.78
0.16 ± 0.07

%ID/g indicates percent injected dose per gram of tissue.
Values are the mean ± standard deviation obtained from four rats.
†
P b .05 and ††P b .01 compared with normal rats and ⁎P b .05 and ⁎⁎P b .01 compared with
EHBR rats.

of [ 99mTc]MAG3 for MRP4 was higher than that for MRP2 because theaverage Km values of [ 99mTc]MAG3 were 8.1 μM for MRP2 and 4.5 μM
for MRP4.
Normal rats express MRP2 [6] and MRP4 [7], whereas EHBR rats lackfunctional MRP2. We estimated that EHBR rats with MK-571 loading
would lack function of both MRP2 and MRP4. The average Tmax values
were thought to be similar in normal and EHBR rats because both
OAT1 and OAT3 are expressed on the basolateral membrane in bothtypes of rats and because MRP4 would be more involved in the transport on the apical membrane in renal proximal tubule cells than MRP2
in EHBR rats. On the other hand, MK-571-loaded EHBR rats that wereadministered [ 99mTc]MAG3 showed a slower Tmax than the other rats,
which may be because MK-571 inhibits not only MRP but also partiallyinhibits OAT [8]; thus, [ 99mTc]MAG3 uptake on the basolateral membrane was inhibited in MK-571-loaded EHBR rats.
The difference in the T1/2 and AUC values between normal and EHBR
rats showed that MRP2 was involved in [ 99mTc]MAG3 transport. MK571 loading was thought to partially inhibit the function of MRP4 on
the renal apical membrane, which led to the delay in the T1/2 value in
MK-571-loaded EHBR rats compared to normal and EHBR rats. Although
the afﬁnity of MRP4 was higher than that of MRP2 in vitro (Fig. 3), theeffect of MRP4 would be smaller than that of MRP2 regarding T1/2 andAUC values because the effect of MK-571 was transient after the injection. Regarding the bladder accumulation of [ 99mTc]MAG3, normal rats
showed the highest accumulation, followed by EHBR rats and then
EHBR rats with MK-571 loading. MK-571 loading for transient MRP4 inhibition in EHBR rats provided signiﬁcant inhibition. Therefore, we conﬁrmed that [99mTc]MAG3 was transported via MRP2 and MRP4 in vivo.
In biological distribution of [ 99mTc]MAG3 (Table 1), radioactivity ofkidney and bladder in all rat groups were similar with time activity
curves derived from SPECT images (Fig. 4b and c). Because radioactivityof bladder in EHBR rats and EHBR rats with MK-571 loading was lower
than that in normal rats, the effect of MRP2 and MRP4 for efﬂux of[ 99mTc]MAG3 was found, but the effect of MRP4 inhibition in EHBR
rats with MK-571 was smaller than the effect of MRP2 deﬁciency in
EHBR rats like Fig. 4c because of transient MK-571 inhibition although
MK-571 yielded higher radioactivity in blood than normal and EHBR
rats due to OAT inhibition.
This study showed the transport mechanism of [99mTc]MAG3 in kidney, and suggested that MRP2 and MRP4 were involved in secretion of[ 99mTc]MAG3 from proximal tubule cells into urea and that MRP inhibitors may affect the pharmacokinetics of [ 99mTc]MAG3. Taylor reported
that patients with renal failure show a change in the biodistribution of

M. Kobayashi et al. / Nuclear Medicine and Biology 84–85 (2020) 33–37[ 99mTc]MAG3 and an increase in accumulation in the gallbladder compared with normal subjects [9]. If the reason for these observations is
low function of MRP4 on the renal apical membrane due to renal failure,
the normal function of MRP2 that is expressed on the bile canalicularmembrane may be involved in the increase in accumulation in the gallbladder of [99mTc]MAG3. Thus, our ﬁndings may be helpful for deciding
on the use of [ 99mTc]MAG3 or the interpretation of the distribution of[ 99mTc]MAG3.
5. Conclusion[ 99mTc]MAG3 is transported via OAT1 and OAT3 on the basolateral
membrane from blood into tubular epithelial cells and then via MRP2
and MRP4 on the apical membrane from the cells into urine. The afﬁnityof [99mTc]MAG3 for MRP4 is higher than that for MRP2.
Financial support
This study was partly funded by Grants-in-Aid for Scientiﬁc Researchfrom the Japan Society for the Promotion of Science (Nos. 16KK0200
and 18K07747).
Declaration of competing interest
Hiroyuki Okudaira is an employee of Nihon Medi-Physics Co., Ltd.
Acknowledgments
The authors thank the staff of the School of Health Sciences, Kanazawa University and Nihon Medi-Physics Co., Ltd. for their technicalsupport. This study was partly funded by Grants-in-Aid for Scientiﬁc Re-

37

search from the Japan Society for the Promotion of Science (Nos.
16KK0200 and 18K07747).
Ethical approval
All applicable institutional guidelines for the care and use of animals
were followed at Kanazawa University. All procedures performed instudies involving animals were in accordance with the ethical standardsof Kanazawa University (the Animal Care Committee of Kanazawa University, AP-122340).
References[1] Russell CD, Dubovsky EV. Reproducibility of single-sample clearance of 99mTcmercaptoacetyltriglycine and 131I-orthoiodohippurate. J Nucl Med 1999;40(7):1122–4.
[2] Shikano N, Kanai Y, Kawai K, Ishikawa N, Endou H. Transport of 99mTc-MAG3 via rat
renal organic anion transporter 1. J Nucl Med 2004;45(1):80–5.
[3] Takahara N, Saga T, Inubushi M, Kusuhara H, Seki C, Ito S, et al. Drugs interacting withorganic anion transporter-1 affect uptake of Tc-99m-mercaptoacetyl-triglycine(MAG3) in the human kidney: therapeutic drug interaction in Tc-99m-MAG3 diagnosis of renal function and possible application of Tc-99m-MAG3 for drug development.
Nucl Med Biol 2013;40(5):643–50.
[4] Yin J, Wang J. Renal drug transporters and their signiﬁcance in drug-drug interactions.
Acta Pharm Sin B 2016;6(5):363–73.
[5] Morrissey KM, Stocker SL, Wittwer MB, Xu L, Giacomini KM. Renal transporters in
drug development. Annu Rev Pharmacol Toxicol 2013;53:503–29.
[6] Chen C, Slitt AL, Dieter MZ, Tanaka Y, Scheffer GL, Klaassen CD. Up-regulation of Mrp4
expression in kidney of Mrp2-deﬁcient TR- rats. Biochem Pharmacol 2005;70(7):1088–95.
[7] Chen C, Klaassen CD. Rat multidrug resistance protein 4 (Mrp4, Abcc4): molecularcloning, organ distribution, postnatal renal expression, and chemical inducibility.
Biochem Biophys Res Commun 2004;317(1):46–53.
[8] Henjakovic M, Hagos Y, Krick W, Burckhardt G, Burckhardt BC. Human organic aniontransporter 2 is distinct from organic anion transporters 1 and 3 with respect to transport function. Am J Physiol Renal Physiol 2015;309(10):F843–51.
[9] Taylor Jr A, Eshima D, Christian PE, Wooten WW, Hansen L, McElvany K. Technetium99m MAG3 kit formulation: preliminary results in normal volunteers and patientswith renal failure. J Nucl Med 1988;29(5):616–22.