Non-Coplanar PCB Effects on Skeletal and Cardiac Muscle in the Rainbow Trout

Despite their ban in the 1970’s polychlorinated biphenyls (PCB) still remain widely dispersed in the environment and are among the most commonly detected contaminants in fish tissue.  Research in fish has focused on toxic effects of coplanar or dioxin-like congeners which alter detoxification and endocrine pathways.  Non-coplanar (ncPCB) , or non-dioxin like congeners have received far less regulatory attention but account for approximately 50% of the burdens found in aquatic ecosystems.  In mammals, ncPCBs activate the ryanodine receptor a calcium release channel necessary for excitation-contraction in skeletal and cardiac muscle.  Here, ncPCBs cause the receptor to remain in the open state leading to excess calcium release and loss of muscle function.  Given the important role of this receptor in muscle contraction altering its activity could have drastic impacts on swimming behavior and neuromuscular function in teleosts.  We use in vitro assays to address this issue looking at single ncPCBs or environmentally relevant congener mixtures on rainbow trout skeletal and cardiac muscle.  We have found that PCB95, the most potent congener, leads to a 300 fold increase in receptor activity in fish skeletal muscle.   These investigations, combined with research on dioxin-like congeners, provide a better understanding of PCB’s impact on important ecological and economical fish species.