In vivo imaging of reactive small molecule metabolites with high spatial resolution and specificity could give clues to understanding pathophysiology of various diseases. We herein applied time of flight-secondary ion mass spectrometry (TOF-SIMS) to newly developed silverdeposited plates that were stamped on mouse tissues, and succeeded in visualization of halide (Cl-, Br-, and I-) and pseudohalide thiocyanate (SCN-) anions, a class of substrates for neutrophils/eosinophil peroxidases to produce hypohalous acids (HOX/OX- mixture; X: (pseudo) halides) , as well as hydrogen sulfide (H2S) . Forty-micrometer frozen mouse kidney sections on cover glasses were attached to 37 °C preheated silver-deposited plates and incubated at -10 °C for 1 h. After sputter cleaning to remove surface contaminants, the plates were analyzed by TOF-SIMS to identify distribution of Br-, AgBr 2-, I-, AgI 2 -, SCN-, as well as S 2- and AgS- as products of tissue-derived H 2S. Br-, AgBr 2 -, I-, and SCN- anions were mainly distributed in core regions including the inner medulla and inner stripe of the outer medulla (except for I-) , rather than outer regions such as the cortex and outer stripe of the outer medulla. AgI 2 - anion was spread over the whole kidney, although its levels were relatively low. In contrast, S 2- and AgS- anions were mainly present in the outer regions. To our knowledge, this is the first imaging study to reveal the distribution of (pseudo) halides and H 2S in animal tissue sections.
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