Figure 3
Effect of EGTA on [Ca2+]i and ERK 1/2 activation. A: [Ca2+]i measurements. Hepatocytes were preincubated in Krebs-Ringer-Hepes buffer with or without 5 mM EGTA for 15 min after fura-2 AM loading. After 60 seconds of registration the cells were stimulated with norepinephrine (10 μM) in the presence of timolol (10 μM). Results show a typical single cell response. B-D: ERK1/2 responses. Hepatocytes cultured for 3 h were pretreated with timolol (10 μM) for 30 min and EGTA (5 mM) for 15 min before stimulation with norepinephrine (10 μM), TPA (1 μM), thapsigargin (1 μM), A23187 (10 μM) or PGF2α (10 μM) for 5 min (in the presence of 0.5 % DMSO). B: Activity measurements of ERK1/2 representing the mean ± S.E.M. of three experiments. C, D: Immunoblots using antibody against double phosphorylated, i.e. activated, forms of ERK1/2.