Figure 1.

(a) Photograph of the rat kidney during sectioning with labeled regions corresponding to the following mass spectra. (b–f) Native mass spectra from distinct regions of the kidney. Some proteins exhibited strong signals in one region, e.g., H-FABP in the medulla (b), regucalcin in the cortex (c), and adipocyte lipid-binding protein in the renal pelvis (f). Spectra are the result of averaging multiple orbitrap scans ((b): 48, ∼0.096 mm² of tissue sampled, (c): 148, ∼0.3 mm², (d): 18, ∼0.036 mm², (e): 22, ∼0.044 mm², (f): 188, ∼0.376 mm²) from raster line scans acquired at 20 μm/s in the respective region of tissue to improve the signal-to-noise ratio.