Fig. 3.

Gly-Sar- but not peptone-stimulated GLP-1 secretion relies on activation of L-type Ca²⁺ channels. (a) Mixed primary cultures from murine colon were incubated for 2 h under control conditions (standard bath solution) with (n = 9) or without (n = 18) nifedipine (10 μmol/l) or in the presence of Gly-Sar (10 mmol/l) with (n = 8) or without (n = 18) the addition of nifedipine, as indicated. (b) Mixed primary cultures from murine colon were incubated for 2 h under control conditions (standard bath solution) with (n = 6) or without (n = 12) nifedipine (10 μmol/l) or in the presence of 5 mg/ml peptone (with [n = 12] and without [n = 12] nifedipine) or 50 mg/ml peptone (with [n = 6] and without [n = 6] nifedipine), as indicated. GLP-1 secretion in each well is expressed relative to the basal secretion (control) measured in parallel on the same day and indicated by the dashed line. Data represent the mean ± SEM. **p < 0.01, ***p < 0.001 compared with their respective controls by one-way ANOVA with post hoc Dunnett’s test