Genetic regulation of aryl hydrocarbon hydroxylase activity in cultures of mouse fetal liver cells.

Primary cultures of fetal liver cells were established from six inbred strains of mice to determine whether the genes regulating the induction of aryl hydrocarbon hydroxylase (AHH) in adult livers in vivo also function in fetal liver cells maintained in culture. Fetuses were 19 days old and were derived from three inbred mouse strains (A/J, C3H/HeJ, C57BL/6J) which are classified genetically as aromatic hydrocarbon responsive and three strains (AKR/J, DBA/2J, SWR/J) which are classified as aromatic hydrocarbon non-responsive. Cells were induced with 3-methylcholanthrene (3-MC) and harvested for measurement of AHH activity, DNA content and amount of [3H]thymidine incorporated. The time course of induction of AHH activity by 3-MC was followed from around 60 h after cells were plated until 190 h when cells were at the end of exponential and at the start of stationary growth phase. Both basal and induced AHH activities generally rise to a peak value during exponential growth and then decline as cells reach stationary phase. During late exponential growth to early stationary growth phase, cells derived from responsive strains have higher induced enzyme activity than cells derived from non-responsive strains. Cells from aromatic hydrocarbon responsive mice attained maximal AHH activity with inducer concentrations of 0.05--0.10 micrograms 3-MC/ml. Cells from aromatic hydrocarbon non-responsive strains were maximally induced at 0.50 micrograms 3-MC/ml. The 5--10-fold difference between cells from responsive and non-responsive mice in concentration of 3-MC needed to induce AHH maximally is taken to indicate that genes controlling aromatic hydrocarbon responsiveness in adult mouse livers in vivo also function in fetal mouse liver cells maintained in culture.