Fig. 1. Effects of extracellular magnesium on caspase-3 activation. (A) Time course analysis in a primary culture of human hepatocytes (HH1) exposed to 0, 0.2, 0.4 and 0.8 mM magnesium. (B) Concentration-dependent analysis in three representative primary cultures of human hepatocytes (HH1, HH2 and HH5) and cultures of rat hepatocytes (RH, expressed as means + SEM, n = 3 different hepatocyte cultures, means without a common letter (a, b, c) differ, p 0.05) exposed to 0, 0.2, 0.4 and 0.8 mM magnesium for 72 h. Caspase-3 activities in the 0.8 mM condition are 191.8, 90.9, 243.1 and 9.1 pmol AMC/min/mg protein for HH1, HH2, HH5 and RH, respectively.