FIG. 2.

Chiral NDL-PCBs and their hydroxylated derivatives enhance [³H]Ry binding in a concentration-dependent manner. A, Concentration-effect curves for enhancing the specific binding of [³H]Ry by 4 racemic NDL-PCBs. Equilibrium binding of [³H]Ry to RyR1 was performed in the absence and presence (0–20 µM) of PCB91 (91), PCB95 (95), 5-OH-PCB95 (5-OH), 4-OH-PCB95 (4-OH), PCB132 (132), or PCB149 (149) as described in the Materials and Methods section. The potency and efficacy are summarized in Table 1. B, Concentration-effect relationship for enhancing the specific binding of [³H]Ry by 4-OH- and 5-OH-PCB95 relative to their parent congener PCB95. The binding experiment was repeated in triplicates in at least 2 different tissue preparations, and the averaged results are shown in the figures. Baseline DPM ranged from 1000 to 1500 DPM. Note. The same PCB95 trace was used in both panels (A) and (B). Abbreviation: NDL-PCBs, non–dioxin like polychlorinated biphenyls.