Extended Data Fig. 3: Nutrients elicit defined epithelial Ca²⁺ responses.

a–e’, Representative wide-field images of the mucosal surface of Villin|GCaMP3 mouse jejunum at baseline (t = 0 s) (a–e) and during the application of a’, glucose (300 mM) (n = 3 preparations), b’, acetate (100 mM) (n = 3), c’, l-Phe (100 mM) (n = 3), d’, high K⁺ (75 mM) Krebs (n = 5) to depolarize the mucosa or e’, control Krebs buffer (n = 3). Regions of villi that showed an increase in fluorescence intensity in response to each stimulus are highlighted in blue. For each stimulus, examples of Ca²⁺ transients in selected regions of epithelium (arrowheads) are shown at the bottom (a”–e”). Stimuli were applied from t = 20 s to t = 80 s. The timing and duration of stimulus application are indicated by the blue boxes. Scale bars, 200 µm. Drawing in a is adapted from ref. ³⁰ (Wiley).