Bioimaging TOF-SIMS: localization of cholesterol in rat kidney sections

Here, we show the localization of a whole organic molecule in biological tissue using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Rat kidneys were sectioned by cryoultramicrotomy and dried at room temperature. The samples were covered with a thin silver layer and analyzed in an imaging TOF-SIMS instrument equipped with a Ga(+)-source. The cholesterol signal showed a high concentration in the nuclear areas of the epithelial cells and a lower concentration over areas representing the basal lamina of renal tubules. A more diffuse distribution of cholesterol was also found over areas representing the cytoplasm or plasma membrane of the epithelial cells.