TOF-SIMS imaging of halide/thiocyanate anions and hydrogen sulfide in mouse kidney sections using silver-deposited...

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 silver-deposited 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 (H(2)S). 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(2)S. 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(2)S in animal tissue sections.