Figure 1.

Detection of choline and choline esters in colonic epithelium by DESI‐MS. DESI‐MS ion signals for choline (1st row, m [M⁺] = 104.10699), acetylcholine (2nd row, (m [M⁺] = 146.11756), propionylcholine (3rd row, m [M⁺] = 160.13321) and butyrylcholine (4th row, m [M⁺] = 174.14886) in mucosal preparations of rat distal colon. A spatially resolved analysis of the sample was achieved by performing a line‐scan over the surface of the sample (inset). Relative signal intensities of the analytes are displayed for a mass window of ±5 ppm, after normalization to the highest signal intensity for each substance, set to 100%. All analytes were detected from the mucosa sample only. Data shown were a selected, representative set out of four independent experiments.