Effects of omeprazole on gastric surface pH (pHo) at luminal pH 3 and pH 7. Prior to surgery for imaging, some mice were injected with omeprazole (omepz; 60 mg/kg intraperitoneally). After surgery, the exposed gastric tissue was superfused with (A) pH 3 or (B) pH 7 saline solution. Resting gastric pHo was measured before photodamage, and the maximal change in pHo was recorded after photodamage (post-PD). Results compile n = 7 experiments for each condition in (A), and n = 6–16 for conditions in (B). Data are presented as mean±SE and analysed using ANOVA, with Bonferroni’s post hoc test. *p<0.05 and ***p<0.001 versus lack of omeprazole. #p<0.05 versus the indicated conditions.