Effects of Al on estradiol-induced vitellogenin (VTG) induction were electrophoretically examined in primary hepatocyte cultures in rainbow trout. Hepatocytes were precultured for 2 days and then estradiol-17 beta (E2, 6 x 10(-6) M) and Al (10(-6)-10(-4) M) were added to the incubation medium. The hepatocytes were cultured for 5 more days. Spent media were analyzed by SDS-PAGE and the relative rate of VTG synthesis was evaluated by a measurement of the integrated optical density of the main VTG band and was expressed as the percentage of VTG to total proteins including the VTG. The addition of Al to the incubation medium had no effect on the viability of hepatocytes in the culture. However, it specifically reduced VTG synthesis by hepatocytes in a concentration-dependent way and there was a significant reduction at Al concentrations greater than 6 x 10(-5) M. VTG synthesis by E2-primed hepatocytes was also reduced by Al concentrations of more than 6 x 10(-5) M 2-6 days after Al addition. Enriched Ca concentrations (1.8 to 2.5 or 5.0 mM) in the incubation medium had no protective effect on the reduction of VTG synthesis by Al. These results suggest that the synthesis of VTG is more susceptible to Al than are other hepatocyte-derived proteins.