Effects of PCB 52 and PCB 77 on cell viability, [Ca(2+)](i) levels and membrane fluidity in mouse thymocytes.
Exposure to polychlorinated biphenyls (PCBs) is known to suppress immune system function and this action is usually ascribed to dioxin-like PCBs that act via the Ah receptor. We have studied the effects of one ortho-substituted, non-dioxin-like PCB (PCB 52) and one coplanar, dioxin-like congener (PCB 77) on properties of thymocytes acutely isolated from mice. Viability of thymocytes was dose- and time-dependently reduced by PCB 52 with a threshold concentration of about 1 microM, while there was no effect of PCB 77 on viability at concentrations less than 10 microM. Cell death was detectible within 5 min of exposure. Both congeners caused a dose-dependent increase in [Ca(2+)](i), but the threshold concentration was 1 microM for PCB 52 and 5 microM for PCB 77. However, the cell death was not due to the elevation of [Ca(2+)](i), since it was not reduced by incubation in Ca-free Tyrode's Solution. PCB 52, but not PCB 77, caused an increase in membrane fluidity at a concentration of 5 microM. These observations are consistent with previous results that suggest that ortho-substituted PCB congeners dissolve in cell membrane and cause greater disruption of function than do dioxin-like PCB congeners.
Yilmaz
Bayram
B
Firat University, Department of Physiology, Faculty of Medicine, 23119 Elazig, Turkey.
Sandal
Suleyman
S
Chen
Chang-Hwei
CH
Carpenter
David O
DO
D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007552:Isotonic Solutions / Q000494:pharmacology; D008560:Membrane Fluidity / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
D007552:Isotonic Solutions; C037692:Tyrode's solution; C009407:2,5,2',5'-tetrachlorobiphenyl; D011078:Polychlorinated Biphenyls; D002118:Calcium; C028451:3,4,3',4'-tetrachlorobiphenyl