Cellular Responses to Beta Blocker Exposures in Marine Bivalves
Khan, B., R. Burgess, S. Fogg, M. Cantwell, D. Katz, AND K. Ho. Cellular Responses to Beta Blocker Exposures in Marine Bivalves. National Shellfisheries Association 109th Annual Meeting, Knoxville, TN, March 26 - 30, 2017.
The purpose of this research is to examine cellular responses of marine organisms to environmental exposures to prescription drugs such as antihypertensive beta blockers. Marine filter-feeding bivalves serve as good model organisms to identify molecular initiating events (MIEs) and key events (KEs) indicative of contaminant exposure. Cellular biomarker analyses in marine bivalves allow us to understand how pharmaceuticals, which make their way into the aquatic environment, can affect non-target organisms.
β blockers are prescription drugs used for medical treatment of hypertension and arrhythmias. They prevent activation of adenylate cyclase and increases in blood pressure by limiting cAMP production and protein kinase A activation. After being taken therapeutically, β blockers may make their way to coastal habitats via discharge from waste water treatment plants, posing a potential risk to aquatic organisms. The aim of our research is to evaluate cellular biomarkers of β blocker exposure using two drugs, propranolol and metoprolol, in three commercially important marine bivalves -Crassostrea virginica, Mytilus edulis and Mercenaria mercenaria. Bivalves were obtained from Narragansett Bay (Rhode Island, USA) and acclimated in the laboratory. Following acclimation, gills and hepatopancreas tissues were harvested and separately exposed to 0, 1, 10, 100 and 1000 ng/l of each drug for 24 hours. Samples were preserved for cellular biomarker assays. Elevated cellular damage and changes in enzymatic activities were noted at environmentally relevant concentrations, and M. mercenaria was found to be the most sensitive bivalve out of the three species tested. These studies enhance our understanding of the potential impacts of commonly used prescription medication on organisms in coastal ecosystems, and demonstrate that filter feeders such as marine bivalves may serve as good model organisms to examine the effects of water soluble drugs. Evaluating a suite of biomarkers allows us to better define molecular initiating events and subsequent key events that might be used to develop adverse outcome pathways (AOPs) for unintended environmental exposure to β blockers.