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BACKGROUND: Bisphenol A (BPA) is used to produce polycarbonate plastics and epoxy resins that are widely used in everyday products, such as food and beverage containers, toys, and medical devices. Human biomonitoring studies have suggested that a large proportion of the population may be exposed to BPA. Recent epidemiological studies have reported correlations between increased urinary BPA concentrations and cardiovascular disease, yet the direct effects of BPA on the heart are unknown. OBJECTIVES: The goal of our study was to measure the effect of BPA (0.1-100 µM) on cardiac impulse propagation ex vivo using excised whole hearts from adult female rats. METHODS: We measured atrial and ventricular activation times during sinus and paced rhythms using epicardial electrodes and optical mapping of transmembrane potential in excised rat hearts exposed to BPA via perfusate media. Atrioventricular activation intervals and epicardial conduction velocities were computed using recorded activation times. RESULTS: Cardiac BPA exposure resulted in prolonged PR segment and decreased epicardial conduction velocity (0.1-100 µM BPA), prolonged action potential duration (1-100 µM BPA), and delayed atrioventricular conduction (10-100 µM BPA). These effects were observed after acute exposure (≤ 15 min), underscoring the potential detrimental effects of continuous BPA exposure. The highest BPA concentration used (100 µM) resulted in prolonged QRS intervals and dropped ventricular beats, and eventually resulted in complete heart block. CONCLUSIONS: Our results show that acute BPA exposure slowed electrical conduction in excised hearts from female rats. These findings emphasize the importance of examining BPA's effect on heart electrophysiology and determining whether chronic in vivo exposure can cause or exacerbate conduction abnormalities in patients with preexisting heart conditions and in other high-risk populations. CITATION: Posnack NG, Jaimes R III, Asfour H, Swift LM, Wengrowski AM, Sarvazyan N, Kay MW. 2014. Bisphenol A exposure and cardiac electrical conduction in excised rat hearts. Environ Health Perspect 122:384-390; http://dx.doi.org/10.1289/ehp.1206157, Introduction Bisphenol A (BPA) is one of the most widely used chemicals worldwide, with > 8 million pounds produced each year (Vandenberg et al. 2010). BPA is a component of [...]