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Application Imaging Mass Microscope

News
A Study of Toxicity Evaluation Using the iMScope TRIO

- Analysis of Localization of Amiodarone in Rat Lungs -
No. B61

In drug discovery research, the analysis of the
pharmacokinetics of candidate compounds provides
important information not only in the elucidation of
pharmacological mechanisms, but also from the
viewpoint of toxicity assessment. In general, a method
using autoradiography (ARG) and fluorescent dye is used,
but with ARG the costs are high, and there have been
concerns about the effects of using fluorescent agents as
labeling agents on the pharmacokinetics. In recent years,
the analytical technique of MS imaging has been
attracting attention as a method that can detect data on
the localization of candidate compounds without using a
label. This method is expected to provide a breakthrough
in drug discovery research as it can be used to analyze the
localization of various substances without labeling, and to
simultaneously analyze the unchanged drug and its
metabolites using the same section.
iMScope TRIO
Here, we introduce an example of MS imaging analysis

using the iMScope TRIO imaging mass microscope (Fig. 2)
Table 1 Experimental Conditions
to compare the localization of the pathological findings
with that of the amiodarone observed in lung tissue after Sample Preparation
Animal species : Rat
administering amiodarone (Fig. 1) to rats.
Administered drug : Amiodarone hydrochloride
R. Yamaguchi, T. Yamamoto Administration method : 3-day repeated oral

administration
„ Analysis of Localization of Amiodarone in Rat Lungs Dose : 1000 mg/kg
Organ : Pulmonary tissue
In this experiment, we measured the tissue sections of rats
Section : Fresh frozen sections
lungs that had been administered amiodarone, an anti- Section thickness : 10 μm
arrhythmia drug. When administered in large quantities,
amiodarone causes phospholipidosis and pathological Matrix Coating
findings such as foamy macrophage infiltration of cells are Matrix : CHCA
Matrix coating method : Sublimation by iMLayer
observed. However, up until now there had been no Matrix coating thickness : 0.7 μm
information on whether amiodarone accumulated in the
lesions or not, so we examined the relationship between Measurement Conditions
the pathological findings and localization of amiodarone Analysis instrument : iMScope TRIO
utilizing the MS imaging technique. In the preliminary Measurement mode : positive mode
study test using standard amiodarone, we optimized the MS range : m/z 500-700
Laser diameter : 5 μm
matrix selection and measurement mode, and applied Spatial resolution : 5 μm
those conditions in this experiment. Table 1 shows the
experimental conditions from sample preparation to MS
imaging analysis. 7.5 (x1,000,000) 646.037
On comparing the mass spectrum taken from a tissue 5.0
section obtained by performing high-resolution imaging 2.5
with a spatial resolution of 5 μm using the iMScope TRIO 506.139 518.123 550.130 568.141 584.186 618.005 634.000 662.032
0.0
with the mass spectrum of the standard, a common 500.0 525.0 550.0 575.0 600.0 625.0 650.0 675.0 700.0
m/z
m/z 646.0 signal was detected (Fig. 3). By drawing a mass Mass spectrum taken from the tissue section
image of this m/z 646.0, we confirmed that amiodarone (x10,000,000)
had accumulated where foamy macrophages had 1.00 646.056
0.75
infiltrated the cells (Fig. 4). 0.50 518.126
0.25
502.086
579.246 630.001
0.00
500.0 525.0 550.0 575.0 600.0 625.0 650.0 675.0 700.0
m/z
Mass spectrum of standard

Mass Spectra of the Tissue Section and Standard

Structural Formula of Amiodarone