Figure 4.

Effects of Hv1 on β-cell mass, size and number of insulin granules, and docking of vesicles. A, immunohistochemical analysis of 4-month-old WT, Hv1^+/−, and Hv1^−/− islets using anti-insulin and anti-glucagon antibodies and representative images of H&E–, anti-insulin–, and anti-glucagon antibody–stained pancreatic sections from 4-month-old WT, Hv1^+/−, and Hv1^−/− mice. Scale bar = 50 μm. B and C, relative islet number based on immunohistochemical analysis of pancreatic sections (B) and islet size calculated by isolated islet area (C) in 4-month-old WT and Hv1^−/− mice (n = 6/genotype). Data are means ± S.E. NS, no significance; *, p < 0.05 versus WT. D, relative islet area of 4-month-old WT and Hv1^−/− mice analyzed by immunohistochemistry of pancreatic sections (n = 6/genotype). Data are means ± S.E. *, p < 0.05 versus WT. E, β-cell mass of 4-month-old WT and Hv1^−/− mice based on immunostaining of pancreatic sections (n = 6/genotype). Relative β-cell mass was determined as a ratio of total insulin-positive area to total pancreatic area. Twenty to thirty sections per pancreas were analyzed. Data are presented as mean ± S.E. *, p < 0.05 versus WT. F, pancreatic insulin content (n = 6/genotype). Data are mean ± S.E. *, p < 0.05 versus WT. G, representative TEM images of β-cells from 4-month-old WT and KO mice. Scale bar = 2 μm. H, relative size distribution of vesicles in β-cells based on TEM images. The size of vesicles in KO mice is smaller than in WT mice (n = 50/genotype). Data are means ± S.E. *, p < 0.05 versus WT. I, vesicle density in pancreatic β-cells of 4-month-old WT and KO mice analyzed by TEM images (n = 50/genotype). Data are means ± S.E., versus WT. J, number of vesicles docked onto the cytoplasmic membrane in β-cells of WT and KO islets from TEM-based analysis (n = 50/genotype). Data are means ± S.E., versus WT. K, expression of tubulin, Stx1a, Syt7, and Vamp2 in isolated islets from WT and KO mice, as determined by Western blotting.