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- Title
Structure-Activity Relationship of Selected Meta- and Para-Hydroxylated Non–Dioxin Like Polychlorinated Biphenyls: From Single RyR1 Channels to Muscle Dysfunction.
- Authors
Niknam, Yassaman; Feng, Wei; Cherednichenko, Gennady; Dong, Yao; Joshi, Sudhir N.; Vyas, Sandhya M.; Lehmler, Hans-Joachim; Pessah, Isaac N.
- Abstract
Non–dioxin like polychlorinated biphenyls (NDL-PCBs) are legacy environmental contaminants with contemporary unintentional sources. NDL-PCBs interact with ryanodine receptors (RyRs), Ca2+ channels of sarcoplasmic/endoplasmic reticulum (SR/ER) that regulate excitation-contraction coupling (ECC) and Ca2+-dependent cell signaling in muscle. Activities of 4 chiral congeners PCB91, 95, 132, and 149 and their respective 4- and 5-hydroxy (-OH) derivatives toward rabbit skeletal muscle ryanodine receptor (RyR1) are investigated using [3H]ryanodine binding and SR Ca2+ flux analyses. Although 5-OH metabolites have comparable activity to their respective parent in both assays, 4-OH derivatives are unable to trigger Ca2+ release from SR microsomes in the presence of Ca2+-ATPase activity. PCB95 and derivatives are investigated using single channel voltage-clamp and primary murine embryonic muscle cells (myotubes). Like PCB95, 5-OH-PCB95 quickly and persistently increases channel open probability (po > .9) by stabilizing the full-open channel state, whereas 4-OH-PCB95 transiently enhances po. Ca2+ imaging of myotubes loaded with Fluo-4 show that acute exposure to PCB95 (5µM) potentiates ECC and caffeine responses and partially depletes SR Ca2+ stores. Exposure to 5-OH-PCB95 (5 µM) increases cytoplasmic Ca2+, leading to rapid ECC failure in 50% of myotubes with the remainder retaining negligible responses. 4-OH-PCB95 neither increases baseline Ca2+ nor causes ECC failure but depresses ECC and caffeine responses by 50%. With longer (3h) exposure to 300nM PCB95, 5-OH-PCB95, or 4-OH-PCB95 decreases the number of ECC responsive myotubes by 22%, 81%, and 51% compared with control by depleting SR Ca2+ and/or uncoupling ECC. NDL-PCBs and their 5-OH and 4-OH metabolites differentially influence RyR1 channel activity and ECC in embryonic skeletal muscle.
- Subjects
HYDROXYLATION; POLYCHLORINATED biphenyls; TOXICOLOGY of dioxins; POLLUTANTS; EXCITATION (Physiology); CELLULAR signal transduction; MUSCLE cells; SKELETAL muscle
- Publication
Toxicological Sciences, 2013, Vol 136, Issue 2, p500
- ISSN
1096-6080
- Publication type
Article
- DOI
10.1093/toxsci/kft202