Biochemical evaluation of rat hepatocyte primary cultures as a model for carbon tetrachloride hepatotoxicity: comparative studies in vivo and in vitro

In order to evaluate how well the development of CCl4 hepatotoxicity in vivo can be modeled in primary cultures of rat hepatocytes, biochemical alterations were determined in liver samples from rats given CCl4 and in liver cells cultured for 18 hr then exposed to CCl4. Soluble thiol levels matched closely between tissue and hepatocytes (11 vs 12 micrograms-SH/mg protein) prior to exposure. Comparable concentrations of CCl4 were measured in blood (0.30 mM at 30 min) and in culture medium (0.49 mM at 5 min). Simultaneous inhibition of the endoplasmic reticulum calcium pump and stimulation of phosphorylase a activity occurred at early times in vivo (30 min) and in vitro (5 min). Glucose-6-phosphatase was inhibited next in liver (120 min) and in cells (20 min). 5'-Nucleotidase was not affected at any time points examined in either system. Leakage of glutamic-pyruvic transaminase and depletion of glycogen were maximal at later times in vivo (greater than or equal to 8 hr) and in cells (30 min). Total calcium content was increased severalfold in liver tissue (24 hr), but was not elevated in hepatocytes. This lack of calcium accumulation in cells appeared to result from impaired mitochondrial calcium uptake. Thus CCl4-induced biochemical changes followed nearly the same continuum in both models, although the progression was much more rapid in vitro than in vivo.