Figure 6.

Effects of glucose and PMA treatment on cytosolic pH and of Hv1 on PMA-stimulated insulin secretion. A, effect of Hv1 on glucose-induced changes in cytosolic pH in isolated islet β-cells, determined by BCECF fluorescence. Glucose (final concentration, 16.7 mm) solution was added to the culture dishes without interruption of the recordings. B, cytosolic pH in β-cells isolated from WT and KO mice in the presence of 2.8 or 16.7 mm glucose (Glc). Data are means ± S.E. (n = 3/genotype). C, representative images of WT and KO islet β-cells loaded with BCECF dye in sodium-free solution to minimize the contribution of Na⁺/H⁺ exchange under basal conditions and in the presence of 5 μm PMA. Scale bar = 100 μm. D, change in fluorescence (F488/F₀) with time, stimulated by PMA (final concentration, 5 μm). The PMA solution was added to the culture dishes without interruption of the recordings. E, PMA-induced insulin secretion from isolated islets from WT and KO mice (n = 8/genotype). Data are means ± S.E. *, p < 0.05; ***, p < 0.001, versus corresponding WT; ###, p < 0.001 versus corresponding WT at 0 μm PMA.