CONGENER-SPECIFIC EFFECTS BY POLYCHLORINATED-BIPHENYLS ON CATECHOLAMINE CONTENT AND RELEASE IN CHROMAFFIN CELLS

The effects of the non-planar polychlorinated biphenyl (PCB) congener 2,2',4,4'-tetrachlorobiphenyl (2,4-TCB) and of the coplanar PCB congen er 3,3',4,4'-tetrachlorobiphenyl (3,4-TCB) were investigated on the ca techolamine content and release from bovine adrenal chromaffin cells i n culture. Each congener was tested at three concentrations (20, 50 an d 100 mu M) and two exposure periods (24 h and 5 days). Catecholamine release induced by K+-stimulation as well as catecholamine content of Triton X-100 treated cell cultures were examined using high-performanc e liquid chromatography (HPLC). 2,4-TCB showed dose- and time-dependen t effects. 2,4-TCB at 100 mu M reduced the K+-stimulated catecholamine release after 24 h of exposure. After 5 days of exposure, 2,4 TCB at 50 and 100 mu M drastically reduced the K+-stimulated catecholamine re lease. 3,4-TCB even at a concentration of 100 mu M over exposure of ei ther 24 h or 5 days had no effects on the K+-stimulated secretion. Whe n chromaffin cells, exposed to 2,4-TCB, were lysed with 0.5% Triton X- 100, a dose- and time-dependent reduction of the catecholamine content appeared. The 3,4-TCB did not reduce the catecholamine content. Conve rsely there seemed to be a trend towards an increase in catecholamine content. Spontaneous release of catecholamines was strongly increased by the non-planar 2,4 TCB, while the coplanar 3,4 TCB showed no effect s on this parameter. Furthermore, the effects of 2,4 TCB appeared to b e reversible after replacing the highest concentration (100 mu M) of t he TCB-solution with culture-medium at the end of the 24-h exposure. T hus, K+-stimulated catecholamine release and the catecholamine content of bovine adrenal chromaffin cells was effectively reduced by the non -planar PCB congener whereas spontaneous catecholamine release was str ongly increased. The coplanar PCB congener was ineffective at the same conditions.