[PCBs cause necrosis of L6C5 myoblasts]

Polychlorinated biphenyls (PCBs) are structurally related to dioxins, widely used in the past in various industrial applications and daily used products. Although PCBs production was discontinued more than twenty years ago, their chemical stability and high lipophilicity make them persistent pollutants and dangerous occupational contaminants. Skeletal muscle is an important site of PCB accumulation. Our previous results about the effects of PCBs on L6C5 myoblasts, showed that "low concentrations" (< 10 microg/ml) of these compounds inhibit in vitro myogenic differentiation in a concentration-dependent fashion, while toxic effects only begin to be evident at PCB concentrations > or = 10 microg/ml. In the present paper we wondered if the observed cell mortality is due to necrosis or if it depends on the activation of programmed cell death mechanisms (apoptosis). Using different methods of analysis, we have observed that PCBs cause necrosis of myogenic cells and that such effect is related to the employed concentrations and to the time of exposure (EC50 approximately = 50 microg/ml). Our results may help to explain the creatin kinase elevation, observed in the blood of patients acutely exposed to high concentrations of PCBs, as the consequence of a necrotic damage of the skeletal muscle. It will be therefore interesting to evaluate the presence of muscular damages in the chronic exposures to PCBs.