Fig. 3. Effects of various dietary acids (x axis) on relative gene expression (y axis) in the antral and corpus (body) regions of rainbow trout stomach. One of the following acids or antacid was added to the basal diet (No acid) (w/w). HCl: 12 mol 1^-1 HCl 5.0%; H₂SO₄h, 18 mol l^-1 H₂SO₄ 3.5%; H₂SO₄L: 18 mol l^-1 H₂SO₄ 1.0%; acetic: glacial acetic acid 5.0%; antacid: CaCO₃ 5.0%. No acid: basal diet (see Table 1). Gray bars represent data of corpus stomach; white bars represent data of antral stomach. Each column represents the average (+ s.e.m. as error bar) of four fish. Columns within each stomach region labeled with different letters are significantly different (P<0.05). ATP4A, H⁺/K⁺-ATPase; SST, somatostatin; NBC, Na⁺/bicarbonate cotransporter). Differences of mRNA abundance between antral and corpus stomach (all treatments inclusive) were as follows: Gastrin-like gene (P=0.8); ATP4A (P=0.0003); SST1 (P=0.02); SST2 (P=0.002); SST2-2 (P=0.8); NBC (P=0.0007).