The use of primary cultures of adult rat hepatocytes to study induction of enzymes and DNA synthesis: effect of nafenopin and electroporation.

Primary cultures of adult rat hepatocytes maintained in a well-differentiated state, in a chemically defined medium containing 2% DMSO, have been utilized to study the effect of non-mutagenic hepatocarcinogens such as the peroxisome proliferator nafenopin. The parameters chosen in this in vitro system were those that paralleled the major in vivo effects of nafenopin on the liver, mainly: the proliferation of the endoplasmic reticulum and induction of cytochrome P-452, the proliferation of the peroxisome compartment and the induction of cyanide-insensitive beta-oxidation of fatty acids and the stimulation of liver growth as measured by the DNA synthetic activity of the hepatocytes. In this review, we also describe the morphology of hepatocyte cultures prepared from previously electroporated hepatocytes and the potential for the use of electroporation to introduce growth related genes into hepatocyte cells to study the mechanisms of hepatocyte growth at the molecular level. In addition we describe the formation of endoplasmic reticulum whorls in these cultures as a consequence of nafenopin treatment. 'Whorl formation' by hepatotrophic chemicals has been previously shown to occur in vivo; in this report, it is described for the first time in vitro.