Figure 2. Ammonia treatment induces locally upregulation of calcium concentration. (A) For intracellular calcium staining, 2 μM calcein-AM or 2 μM Fluo-4 were added to culture medium for 30 min before image capture. Quantitative data of number of calcein puncta (B) or Fluo-4 sparks (C) indicate high concentrations of calcium. Data are means ± SEs from at least three independent experiments; * p < 0.05 vs. Ctrl. Scale bar, 20 μm.