Efficient accumulation of PCBs in primary cultures of rat adipocytes: A tool to study the toxicokinetics of these persistent organic pollutants

Abstract

Purpose: We investigated the process of bio-accumulation of 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126) in cultured rat adipocytes, both in quantitative and kinetic terms. Methods: [3H]-labelled PCB-126 was added in the medium of primary cultures of rat adipocytes at the concentration of 2.5 nM. After 0.5, 1, 2, 4 and 8 h of incubation, media were collected for residual PCB-126 analysis and cells were harvested for stored PCB-126, triacylglycerols and protein quantification. The experiment was performed on cells, both at day 7 and 13 of the differentiation. Results: The process of adipocyte differentiation was followed through the changes in the cellular content in proteins and triacylglycerols. It appeared to be progressive and was fully accomplished on day 13. Days 7 and 13 were thus chosen for further experiments. In both conditions, the adipocytes were shown to accumulate PCB-126 very effectively. After 30 min, the 7-day cells had already accumulated 7% of the initial PCB quantity, whereas a value of 14% was registered for the 13-day cells. After 8 h, the accumulated amounts reached 29% and 69%, respectively. In average, the cells accumulated two times more pollutants on day 13 than on day 7. When the accumulated PCB-126 amounts were expressed per protein unit, the results were comparable for both days whereas when expressed per unit of triacylglycerols, they appeared significantly lower for the 13-day cells. The PCB-126 intracellular concentration was estimated to be between 80 and 440 times higher than in the medium after a contact time of 8 h.