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Background: Exposure to phenols has been linked in animal models and human populations to cardiac function alterations and cardiovascular diseases, although their effects on cardiac electrical properties in humans remains to be established. This study aimed to identify changes in electrocardiographic (ECG) parameters associated with environmental phenol exposure in adults of a midwestern large cohort known as the Fernald Community Cohort (FCC)., Methods: During the day of the first comprehensive medical examination, urine samples were obtained, and electrocardiograms were recorded. Cross-sectional linear regression analyses were performed., Results: Bisphenol A (BPA) and bisphenol F (BPF) were both associated with a longer PR interval, an indication of delayed atrial-to-ventricle conduction, in females (p < 0.05) but not males. BPA combined with BPF was associated with an increase QRS duration, an indication of delayed ventricular activation, in females (P < 0.05) but not males. Higher triclocarban (TCC) level was associated with longer QTc interval, an indication of delayed ventricular repolarization, in males (P < 0.01) but not females. Body mass index (BMI) was associated with a significant increase in PR and QTc intervals and ventricular rate in females and in ventricular rate in males. In females, the combined effect of being in the top tertile for both BPA urinary concentration and BMI was an estimate of a 10% increase in PR interval. No associations were found with the other phenols., Conclusion: Higher exposure to some phenols was associated with alterations of cardiac electrical properties in a sex specific manner in the Fernald cohort. Our population-based findings correlate directly with clinically relevant parameters that are associated with known pathophysiologic cardiac conditions in humans., (© 2024. The Author(s).)

Bisphenol A (BPA) and its analogs are common environmental chemicals with various adverse health impacts, including cardiac toxicity. In this study, we examined the long term effect of low dose BPA and three common BPA analogs, bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF), in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) based models. HiPSC-CMs and human cardiac organoids were exposed to these chemicals for 4-5 or 20 days. 1 nM BPA, BPS, and BPAF, but not BPF, resulted in suppressed myocyte contractility, retarded contraction kinetics, and aberrant Ca 2+ transients in hiPSC-CMs. In cardiac organoids, BPAF and BPA, but not the other bisphenols, resulted in suppressed contraction and Ca 2+ transients, and aberrant contraction kinetics. The order of toxicities was BPAF > BPA>∼BPS > BPF and the toxicities of BPAF and BPA were more pronounced under longer exposure. The impact of BPAF on myocyte contraction and Ca 2+ handling was mediated by reduction of sarcoplasmic reticulum Ca 2+ load and inhibition of L-type Ca 2+ channel involving alternation of Ca 2+ handling proteins. Impaired myocyte Ca 2+ handling plays a key role in cardiac pathophysiology and is a characteristic of cardiac hypertrophy; therefore we examined the potential pro-hypertrophic cardiotoxicity of these bisphenols. Four to five day exposure to BPAF did not cause hypertrophy in normal hiPSC-CMs, but significantly exacerbated the hypertrophic phenotype in myocytes with existing hypertrophy induced by endothelin-1, characterized by increased cell size and elevated expression of the hypertrophic marker proBNP. This pro-hypertrophic cardiotoxicity was also occurred in cardiac organoids, with BPAF having the strongest toxicity, followed by BPA. Our findings demonstrate that long term exposures to BPA and some of its analogs cause contractile dysfunction and abnormal Ca 2+ handling, and have potential pro-hypertrophic cardiotoxicity in human heart cells/tissues, and suggest that some bisphenol chemicals may be a risk factor for cardiac hypertrophy in human hearts., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Bisphenol A (BPA) is a common environmental chemical with a range of potential adverse health effects. The impact of environmentally-relevant low dose of BPA on the electrical properties of the hearts of large animals (e.g., dog, human) is poorly defined. Perturbation of cardiac electrical properties is a key arrhythmogenic mechanism. In particular, delay of ventricular repolarization and prolongation of the QT interval of the electrocardiogram is a marker for the risk of malignant arrhythmias. We examined the acute effect of 10 -9  M BPA on the electrical properties of female canine ventricular myocytes and tissues. BPA rapidly delayed action potential repolarization and prolonged action potential duration (APD). The dose response curve of BPA on APD was nonmonotonic. BPA rapidly inhibited the I Kr K + current and I CaL Ca 2+ current. Computational modeling indicated that the effect of BPA on APD can be accounted for by its suppression of I Kr . At the tissue level, BPA acutely prolonged the QT interval in 4 left ventricular wedges. ERβ signaling contributed to the acute effects of BPA on ventricular repolarization. Our results demonstrate that BPA has QT prolongation liability in female canine hearts. These findings have implication for the potential proarrhythmic cardiac toxicity of BPA in large animals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Invertebrates are recognized as important species in endocrine disrupting chemical (EDC) testing. However, it is poorly understood whether the effects of EDCs in invertebrates are mediated by hormonal mechanisms. Previously, we showed that bisphenol A (BPA) affected the physiology of the freshwater oligochaete Lumbriculus variegatus. In the present study, we examined the mechanism of the impact of BPA on L. variegatus, using pulse rate of the dorsal blood vessel (DBV) as an endpoint. Both long term and acute exposures to BPA increased the pulsing rate of DBV. The former had a distinct inverted-U dose response relationship with a most efficacious dose of 10 -9  M, which increased the pulse rate from 8.97 to 10.9 beats/min. The effects of BPA were mimicked by the synthetic estrogen ethinylestradiol with a most efficacious dose of 10 -12  M. Interestingly E 2 had no effect on pulsing rate, either acute or long term. The sensitivity of L. variegatus to estrogens were exquisite, with detectable effects at 10 -14 to 10 -10  M range. Both the long term and acute effects of BPA were partially or fully blocked by various vertebrate estrogen receptor (ER) antagonists, including ICI 182,780, MPP and G15. Our results suggest that the impact of BPA on pulsing rate of L. variegatus is likely mediated by an estrogenic mechanism instead of general toxicity. The exceptionally high sensitivity of L. variegatus to some estrogens makes it a possible tool for estrogenic EDC screening., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The aerial parts of Tetrastigma hemsleyanum (APTH) have been used as a functional tea in China. The purpose of the current study was to identify the bioactive constituents with inhibitory activity against soluble epoxide hydrolase (sEH) and inducible nitric oxide synthase (iNOS), which are jointly considered potential therapeutic targets for vascular system diseases. In the present study, 39 compounds (1-39) were isolated from the APTH. Among them, compounds 8, 10, 12, 16, 17, 19, and 32 displayed potential activities, with IC 50 values ranging from 4.5 to 9.5 µM, respectively, and all in non-competitive inhibition mode. Compounds 5, 10, 12, 19, and 32 displayed potent iNOS inhibitory effects, with IC 50 values ranging from 15.6 to 47.3 µM. The results obtained in this work contribute to a better understanding of the pharmacological activities of T. hemsleyanum and its potential application as a functional food.

Bisphenol A (BPA) is a component of polycarbonate plastics and a near ubiquitous environmental endocrine disrupting chemical. Bisphenol S (BPS), a substitute of BPA, is also hormonally active. This study examines the effects of aqueous exposure to BPA and BPS on the freshwater annelids Lumbriculus variegatus, a keystone species in shallow water ecosystems. Both BPA and BPS, at both low dose (10 -9 M) and high dose (10 -6 M), retarded the initial phase of body regrowth after cutting/fragmentation, which is the main mode of reproduction of L. variegatus. Both acute and five day exposure to BPA and BPS increased pulse rate of the dorsal blood vessel. For all the measured endpoints, the effects of BPA and BPS were nearly indistinguishable. These results indicate that BPA and BPS have similar and significant effects on the physiology of L. variegatus. These findings have implication for the potential impact of these bisphenols on invertebrates in the ecosystem., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Bisphenol A (BPA) is an estrogenic endocrine-disrupting chemical (EDC) that has a range of potential adverse health effects. Previously we showed that acute exposure to BPA promoted arrhythmias in female rat hearts through estrogen receptor rapid signaling. Progesterone (P4) and estrogen have antagonistic or complementary actions in a number of tissues and systems. In the current study, we examined the influence and possible protective effect of P4 on the rapid cardiac actions of BPA in female rat cardiac myocytes. Preincubation with physiological concentration (1 nM) of P4 abolished BPA-induced triggered activities in female cardiac myocytes. Further, P4 abrogated BPA-induced alterations in Ca2+ handling, including elevated sarcoplasmic reticulum Ca2+ leak and Ca2+ load. Key to the inhibitory effect of P4 is its blockade of BPA-induced increase in the phosphorylation of phospholamban. At myocyte and protein levels, these inhibitory actions of P4 were blocked by pretreatment with the nuclear P4 receptor (nPR) antagonist RU486. Analysis using membrane-impermeable bovine serum albumin-conjugated P4 suggested that the actions of P4 were mediated by membrane-initiated signaling. Inhibitory G (Gi) protein and phophoinositide-3 kinase (PI3K), but not tyrosine protein kinase activation, were involved in the observed effects of P4. In conclusion, P4 exerts an acute protective effect against BPA-induced arrhythmogenesis in female cardiac myocytes through nPR and the Gi/PI3K signaling pathway. Our findings highlight the importance of considering the impact of EDCs in the context of native hormonals and may provide potential therapeutic strategies for protection against the cardiac toxicities associated with BPA exposure., (Copyright © 2017 Endocrine Society.)

Epidemiologic studies and studies in rodents point to potential risks from developmental exposure to BPA on cardiometabolic diseases. Furthermore, it is becoming increasingly evident that the manifestation and severity of adverse outcomes is the result of interaction between developmental insults and the prevailing environment. Consistent with this premise, recent studies in sheep found prenatal BPA treatment prevented the adverse effects of postnatal obesity in inducing hypertension. The gene networks underlying these complex interactions are not known. mRNA-seq of myocardium was performed on four groups of four female sheep to assess the effects of prenatal BPA exposure, postnatal overfeeding and their interaction on gene transcription, pathway perturbations and functional effects. The effects of prenatal exposure to BPA, postnatal overfeeding, and prenatal BPA with postnatal overfeeding all resulted in transcriptional changes (85-141 significant differentially expressed genes). Although the effects of prenatal BPA and postnatal overfeeding did not involve dysregulation of many of the same genes, they affected a remarkably similar set of biological pathways. Furthermore, an additive or synergistic effect was not found in the combined treatment group, but rather prenatal BPA treatment led to a partial reversal of the effects of overfeeding alone. Many genes previously known to be affected by BPA and involved in obesity, hypertension, or heart disease were altered following these treatments, and AP-1, EGR1, and EGFR were key hubs affected by BPA and/or overfeeding. Environ. Mol. Mutagen. 58:4-18, 2017. © 2016 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Triple-negative breast cancer (TNBC) is characterized by great metastasis and invasion capability. Our study revealed that nanomolar bisphenol A (BPA), one of the most ubiquitous endocrine disruptors, can increase wound closure and invasion of both MDA-MB-231 and BT-549 cells. BPA treatment can increase protein and mRNA expression of matrix metalloproteinase-2 (MMP-2) and MMP-9, while had no effect on the expression of vimentin (Vim) and fibronectin (FN) in TNBC cells. The expression of G-protein-coupled receptor (GPER), which has been suggested to mediate rapid oestrogenic signals, was not varied in BPA-treated MDA-MB-231 and BT-549 cells. Its inhibitor G15 also had no effect on BPA-induced MMPs expression and cell invasion. Interestingly, BPA treatment can significantly increase the mRNA and protein expressions of oestrogen-related receptor γ (ERRγ), but not ERRα or ERRβ, in both MDA-MB-231 and BT-549 cells. The knock-down of ERRγ can markedly attenuate BPA-induced expression of MMP-2 and MMP-9 in TNBC cells. BPA treatment can activate both ERK1/2 and Akt in TNBC cells. Both inhibitors of ERK1/2 (PD98059) and Akt (LY294002) can attenuate BPA-induced ERRγ expression and cell invasion of MDA-MB-231 cells. Collectively, our data revealed that BPA can increase the expression of MMPs and in vitro motility of TNBC cells via ERRγ. Both activation of ERK1/2 and Akt participated in this process. Our study suggests that more attention should be paid to the roles of xenoestrogens such as BPA in the development and progression of TNBC., (© 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).)

Estrogen receptor negative (ER-) breast cancer are associated with increased risks for metastasis and high rates of recurrence. Our present study revealed that nanomolar bisphenol A (BPA), a typical endocrine disrupting chemical, promoted the in vitro migration and induced mesenchymal transition (EMT) of ER-breast cancer cells. PCR array revealed that BPA can down regulate 12 and up regulate 2 genes involved in regulation of signal transduction and biological pathways of breast cancer. The down regulated genes included FOXA1, which is a key determinant of endocrine response and down regulated by BPA via a time dependent manner. Silencing of FOXA1 by siRNA triggered the EMT of SkBr3 cells. While over expression of FOXA1 abolished BPA induced EMT. Further, 10(-8) M BPA significantly increased the phosphorylation of ERK1/2, p38-MAPK, and Akt in SkBr3 cells, while only PI3K/Akt inhibitor LY294002 attenuated the BPA induced down regulation of FOXA1 and E-Cadherin (E-Cad). Over expression of Akt also suppressed FOXA1 expression in SkBr3 cells. It suggested that PI3K/Akt mediated, at least partially, BPA induced EMT of ER-breast cancer cells. In summary, our data provided the first evidence that BPA can promote the EMT of ER-breast cancer cells through down regulation of FOXA1., (Copyright © 2015 Elsevier Inc. All rights reserved.)

More and more evidences indicate that endocrine disruptor chemicals such as bisphenol A (BPA) can act as carcinogens and enhance susceptibility to tumorigenesis. Although the gut is in direct contact with orally ingested BPA, effects of BPA on occurrence and development of colorectal cancer remain an unexplored endpoint. Colorectal cancer SW480 cells treated with nanomolar (10(-8) M) or greater (10(-5) M) concentrations of BPA were compared with responses of a control group. Proteomic study revealed that more than 56 proteins were modulated following exposure to BPA, which are relevant to structure, motility and proliferation of cells, production of ATP, oxidative stress, and protein metabolism. Further studies revealed that BPA increased migration and invasion and triggered transformations from epithelial to mesenchymal transitions (EMTs) of colorectal cancer cells, which was characterized by acquiring mesenchymal spindle-like morphology and increasing the expression of N-cadherin with a concomitant decrease of E-cadherin. Accordingly, BPA treatment increased the expression of transcription factor Snail. Furthermore, signal AKT/GSK-3β-mediated stabilization of Snail is involved during BPA-induced EMT of colon cancer cells. Our study first demonstrated that the xenoestrogen BPA at nanomolar and greater concentrations modulates the protein profiles and promotes the metastasis of colorectal cancer cells via induction of EMT.

Background: Bisphenol S (BPS) has increasingly been used as a substitute for bisphenol A (BPA) in some "BPA-free" consumer goods and in thermal papers. Wide human exposure to BPS has been reported; however, the biological and potential toxic effects of BPS are poorly understood., Objective: In this study, we sought to elucidate the sex-specific rapid effect of BPS in rat hearts and its underlying mechanism., Methods: We examined the rapid effects of BPS in rat hearts using electrophysiology, confocal and conventional fluorescence imaging, and immunoblotting. Treatment was administered via acute perfusion of excised hearts or isolated cardiac myocytes., Results: In female rat hearts acutely exposed to 10-9 M BPS, the heart rate was increased; in the presence of catecholamine-induced stress, the frequency of ventricular arrhythmia events was markedly increased. BPS-exposed hearts showed increased incidence of arrhythmogenic-triggered activities in female ventricular myocytes and altered myocyte Ca2+ handling, particularly spontaneous Ca2+ release from the sarcoplasmic reticulum. The dose responses of BPS actions were inverted U-shaped. The impact of BPS on myocyte Ca2+ handling was mediated by estrogen receptor β signaling and by rapid increases in the phosphorylation of key Ca2+ handling proteins, including ryanodine receptor and phospholamban. The proarrhythmic effects of BPS were female specific; male rat hearts were not affected by BPS at the organ, myocyte, or protein levels., Conclusion: Rapid exposure to low-dose BPS showed proarrhythmic impact on female rat hearts; these effects at the organ, cellular, and molecular levels are remarkably similar to those reported for BPA. Evaluation of the bioactivity and safety of BPS and other BPA analogs is necessary before they are used as BPA alternatives in consumer products.

Background: This study aimed to determine serum Bisphenol A (BPA) concentrations in patients with dilated cardiomyopathy (DCM) as well as the association between serum BPA and several hormonal parameters in DCM patients compared with a healthy control group., Materials and Methods: Eighty-eight DCM patients and 88 age- and gender-matched healthy controls were included. Serum BPA levels and several hormonal parameters (including total testosterone (T), sex hormone-binding globulin (SHBG) and estradiol (E2) were measured by using corresponding ELISA Kits. The free androgen index (FAI) was calculated by the formula: total T in nmol/L × 100/SHBG in nmol/L., Results: BPA levels in the total DCM group were significantly higher compared with that in the controls (6.9 ± 2.7 ng/mL vs. 3.8 ± 1.9 ng/mL, p < 0.001). Significant difference was also observed in SHBG and FAI between DCM patients and controls, (76.9 ± 30.9 nM/L vs. 41.0 ± 15.6 nM/L and 2.9 ± 3.5 vs.5.3 ± 2.6, respectively, both of p < 0.001). Similar trends were observed in the male and female subgroup. Mean T level was lower in DCM group than in control group (540.8 ± 186.0 pg/mL vs. 656.3 ± 112.9 pg/mL, p < 0.001). Linear regression analysis has shown that increasing serum BPA levels were statistically significantly associated with increased SHBG levels. However, no statistical difference was noted for E2., Conclusion: Our findings firstly demonstrated that BPA exposure increased in DCM patients compared with that in healthy controls, while FAI and T levels decreased. SHBG presented a positive association with BPA. It is concluded that hormone disorder induced by BPA exposure might be an environmental factor in the pathology of DCM.

Background: Biphasic effects on cell proliferation of bisphenol A (BPA) can occur at lesser or greater exposures. Sertoli cells play a pivotal role in supporting proliferation and differentiation of germ cells. The mechanisms responsible for inverse effects of great and low concentrations of BPA on Sertoli cell proliferation need further study., Methods: We utilized proteomic study to identify the protein expression changes of Sertoli TM4 cells treated with 10(-8)M and 10(-5)M BPA. The further mechanisms related to mitochondria, energy metabolism and oxidative stress were investigated by qRT-PCR and Western-blotting analysis., Results: Proteomic studies identified 36 proteins and two major clusters of proteins including energy metabolism and oxidative stress expressed with opposite changes in Sertoli cells treated with 10(-8)M and 10(-5)M BPA, respectively, for 24h. Exposure to 10(-5)M BPA resulted in greater oxidative stress and then inhibited cell proliferation, while ROS scavenger NAC effectively blocked these effects. Exposure to 10(-8)M BPA caused higher intercellular ATP, greater activities of mitochondria, and resulted in significant proliferation of TM4 cells, while oligomycin A, an inhibitor of ATP synthase, abolished these growth advantages., Conclusions: Our study demonstrated that micromolar BPA inhibits proliferation of Sertoli cells by elevating oxidative stress while nanomolar BPA stimulates proliferation by promoting energy metabolism., General Significance: Micromolar BPA inhibits cell proliferation by elevating oxidative stress while nanomolar BPA stimulates cell proliferation by promoting energy metabolism., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Bisphenol A (BPA) is a ubiquitous plasticizing agent used in the manufacturing of polycarbonate plastics and epoxy resins. There is well-documented and broad human exposure to BPA. The potential risk that BPA poses to the human health has attracted much attention from regulatory agencies and the general public, and has been extensively studied. An emerging and rapidly growing area in the study of BPA's toxicity is its impact on the cardiovascular (CV) system. Recent epidemiological studies have shown that higher urinary BPA concentration in humans is associated with various types of CV diseases, including angina, hypertension, heart attack and coronary and peripheral arterial disease. Experimental studies have demonstrated that acute BPA exposure promotes the development of arrhythmias in female rodent hearts. Chronic exposure to BPA has been shown to result in cardiac remodeling, atherosclerosis, and altered blood pressure in rodents. The underlying mechanisms may involve alteration of cardiac Ca2+ handling, ion channel inhibition/activation, oxidative stress, and genome/transcriptome modifications. In this review, we discuss these recent findings that point to the potential CV toxicity of BPA, and highlight the knowledge gaps in this growing research area.

Background: The need for mechanistic understanding of nonmonotonic dose responses has been identified as one of the major data gaps in the study of bisphenol A (BPA). Previously we reported that acute exposure to BPA promotes arrhythmogenesis in female hearts through alteration of myocyte Ca(2+) handling, and that the dose response of BPA was inverted U-shaped., Objective: We sought to define the cellular mechanism underlying the nonmonotonic dose response of BPA in the heart., Methods: We examined rapid effects of BPA in female rat ventricular myocytes using video-edge detection, confocal and conventional fluorescence imaging, and patch clamp., Results: The rapid effects of BPA in cardiac myocytes, as measured by multiple end points, including development of arrhythmic activities, myocyte mechanics, and Ca(2+) transient, were characterized by nonmonotonic dose responses. Interestingly, the effects of BPA on individual processes of myocyte Ca(2+) handling were monotonic. Over the concentration range of 10(-12) to 10(-6) M, BPA progressively increased sarcoplasmic reticulum (SR) Ca(2+) release and Ca(2+) reuptake and inhibited the L-type Ca(2+) current (I(CaL)). These effects on myocyte Ca(2+) handling were mediated by estrogen receptor (ER) β signaling. The nonmonotonic dose responses of BPA can be accounted for by the combined effects of progressively increased SR Ca(2+) reuptake/release and decreased Ca(2+) influx through I(CaL)., Conclusion: The rapid effects of BPA on female rat cardiac myocytes are characterized by nonmonotonic dose responses as measured by multiple end points. The nonmonotonic dose response was produced by ERβ-mediated monotonic effects on multiple cellular Ca(2+) handling processes. This represents a distinct mechanism underlying the nonmonotonicity of BPA's actions.

Sertoli cells play a pivotal role in supporting proliferation of germ cells and differentiation during spermatogenesis in mammals. Nanomolar concentrations of Bisphenol A (BPA) can significantly stimulate the proliferation of mouse immature Sertoli (TM4) cells. However, mechanisms by which BPA caused these effects were still unclear. In the present study, an inverse U-shaped curve was observed when treating TM4 cells with increasing doses of BPA: 1 to 10nM BPA significantly stimulated the proliferation of TM4 cells and increased the proportion of cells in S phase; >1 μM BPA caused lesser proliferation of cells. Exposure of TM4 cells to G15 or ICI 182,780, which are specific antagonists of GPR30 and estrogen receptor α/β (ERα/β), respectively, abolished BPA-induced proliferation of cells, which suggests that both GPR30 and ERα/β were involved in the observed effects of BPA. Furthermore, exposure to BPA caused rapid (5 min) activation of ERK1/2 via both GPR30 and ERα/β. Blocking the GPR30/EGFR signal transduction pathway by antagonists suppressed both phosphorylation of ERK and BPA-induced cell proliferation. BPA up-regulated mRNA and protein expression of GPR30 in a concentration-dependent manner. In summary, the results reported here indicated that activating ERK1/2 through GPR30 and ERα/β is involved in low doses of BPA that promoted growth of Sertoli TM4 cells. The GPR30/EGFR/ERK signal is the downstream transduction pathway in BPA-induced proliferation of TM4 Sertoli cells., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Previously we showed that bisphenol A (BPA), an environmental estrogenic endocrine disruptor, rapidly altered Ca(2+) handling and promoted arrhythmias in female rat hearts. The underlying molecular mechanism was not known. Here we examined the cardiac-specific signaling mechanism mediating the rapid impact of low-dose BPA in female rat ventricular myocytes. We showed that protein kinase A (PKA) and Ca(2+)/CaM-dependent protein kinase II (CAMKII) signaling pathways are the two major pathways activated by BPA. Exposure to 1 nM BPA rapidly increased production of cAMP and rapidly but transiently increased the phosphorylation of the ryanodine receptors by PKA but not by CAMKII. BPA also rapidly increased the phosphorylation of phospholamban (PLN), a key regulator protein of sarcoplasmic reticulum Ca(2+) reuptake, by CAMKII but not PKA. The increase in CAMKII phosphorylation of PLN was mediated by phospholipase C and inositol trisphosphate receptor-mediated Ca(2+) release, likely from the endoplasmic reticulum Ca(2+) storage. These two pathways are likely localized, impacting only their respective target proteins. The rapid impacts of BPA on ryanodine receptors and PLN phosphorylation were mediated by estrogen receptor-β but not estrogen receptor-α. BPA's rapid signaling in cardiac myocytes did not involve activation of ERK1/2. Functional analysis showed that PKA but not CAMKII activation contributed to BPA-induced sarcoplasmic reticulum Ca(2+) leak, and both PKA and CAMKII were necessary contributors to the stimulatory effect of BPA on arrhythmogenesis. These results provide mechanistic insight into BPA's rapid proarrhythmic actions in female cardiac myocytes and contribute to the assessment of the consequence and potential cardiac toxicity of BPA exposure.

Bisphenol A (BPA) is an environmental estrogenic endocrine disruptor that may have adverse health impacts on a range of tissue/systems. In previous studies, we reported that BPA rapidly promoted arrhythmias in female rodent hearts through alteration of myocyte calcium handling. In the present study we investigated the acute effects of BPA on ventricular arrhythmias and infarction following ischemia-reperfusion in rat hearts. Rat hearts were subjected to 20 min of global ischemia followed by reperfusion. In female, but not male hearts, acute exposure to 1 nM BPA, either alone or combined with 1 nM 17β-estradiol (E2), during reperfusion resulted in a marked increase in the duration of sustained ventricular arrhythmias. BPA plus E2 increased the duration ventricular fibrillation, and the duration of VF as a fraction of total duration of sustained ventricular arrhythmia. The pro-arrhythmic effects of estrogens were abolished by MPP combined with PHTPP, suggesting the involvements of both ERα and ERβ signaling. In contrast to their pro-arrhythmic effects, BPA and E2 reduced infarction size, agreeing with previously described protective effect of estrogen against cardiac infarction. In conclusion, rapid exposure to low dose BPA, particularly when combined with E2, exacerbates ventricular arrhythmia following IR injury in female rat hearts., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Previously we showed that 17β-estradiol (E(2)) and/or the xenoestrogen bisphenol A (BPA) alter ventricular myocyte Ca(2+) handing, resulting in increased cardiac arrhythmias in a female-specific manner. In the present study, the roles of estrogen receptors (ER) in mediating the rapid contractile and arrhythmogenic effects of estrogens were examined. Contractility was used as an index to assess the impact of E(2) or BPA on Ca(2+) handling in rodent ventricular myocytes. The concentration-response curve for the stimulatory effects of BPA and E(2) on female myocyte was inverted-U shaped. Detectable effects for each compound were observed at 10(-12) M, and the most efficacious concentrations for each were at 10(-9) M. Sensitivity to E(2) and BPA was not observed in male myocytes and was abolished in myocytes from ovariectomized females. Analysis using protein-conjugated E(2) suggests that these rapid actions are induced by membrane-associated receptors. Analysis using selective ER agonists and antagonists and a genetic ERβ knockout mouse model showed that ERα and ERβ have opposing actions in myocytes and that the balance between ERβ and ERα signaling is the prime regulator of the sex-specific sensitivity toward estrogens. The response of female myocytes to E(2) and BPA is dominated by the stimulatory ERβ-mediated signaling, and the absence of BPA and E(2) responsiveness in males is due to a counterbalancing-suppressive action of ERα. We conclude that the sex-specific sensitivity of myocytes to estrogens and the rapid arrhythmogenic effects of BPA and estradiol in the female heart are regulated by the balance between ERα and ERβ signaling.

Background: There is wide-spread human exposure to bisphenol A (BPA), a ubiquitous estrogenic endocrine disruptor that has been implicated as having potentially harmful effects on human heart health. Higher urine BPA concentrations have been shown to be associated with cardiovascular diseases in humans. However, neither the nature nor the mechanism(s) of BPA action on the heart are understood., Methodology/principal Findings: The rapid (<7 min) effects of BPA and 17β-estradiol (E2) in the heart and ventricular myocytes from rodents were investigated in the present study. In isolated ventricular myocytes from young adult females, but not males, physiological concentrations of BPA or E2 (10⁻⁹ M) rapidly induced arrhythmogenic triggered activities. The effects of BPA were particularly pronounced when combined with estradiol. Under conditions of catecholamine stimulation, E2 and BPA promoted ventricular arrhythmias in female, but not male, hearts. The cellular mechanism of the female-specific pro-arrhythmic effects of BPA and E2 were investigated. Exposure to E2 and/or BPA rapidly altered myocyte Ca²⁺ handling; in particular, estrogens markedly increased sarcoplasmic reticulum (SR) Ca²⁺ leak, and increased SR Ca²⁺ load. Ryanodine (10⁻⁷ M) inhibition of SR Ca²⁺ leak suppressed estrogen-induced triggered activities. The rapid response of female myocytes to estrogens was abolished in an estrogen receptor (ER) β knockout mouse model., Conclusions/significance: Physiologically-relevant concentrations of BPA and E2 promote arrhythmias in a female-specific manner in rat hearts; the pro-arrhythmic actions of estrogens are mediated by ERβ-signaling through alterations of myocyte Ca²⁺ handling, particularly increases in SR Ca²⁺ leak. Our study provides the first experimental evidence suggesting that exposure to estrogenic endocrine disrupting chemicals and the unique sensitivity of female hearts to estrogens may play a role in arrhythmogenesis in the female heart.

In addition to regulating estrogen receptor-dependent gene expression, 17beta-estradiol (E(2)) can directly influence intracellular signaling. In primary cultured cerebellar neurons, E(2) was previously shown to regulate growth and oncotic cell death via rapid stimulation of ERK1/2 signaling. Here we show that ERK1/2 signaling in the cerebellum of neonatal and mature rats was rapidly responsive to E(2) and during development to the environmental estrogen bisphenol A (BPA). In vivo dose-response analysis for each estrogenic compound was performed by brief (6-min) intracerebellar injection, followed by rapid fixation and phosphorylation-state-specific immunohistochemistry to quantitatively characterize changes in activated ERK1/2 (pERK) immunopositive cell numbers. Beginning on postnatal d 8, E(2) significantly influenced the number of pERK-positive cells in a cell-specific manner that was dependent on concentration and age but not sex. In cerebellar granule cells on postnatal d 10, E(2) or BPA increased pERK-positive cell numbers at low doses (10(-12) to 10(-10) M) and at higher (10(-7) to 10(-6) M) concentrations. Intermediate concentrations of either estrogenic compound did not modify basal ERK signaling. Rapid E(2)-induced increases in pERK immunoreactivity were specific to the ERK1/2 pathway as demonstrated by coinjection of the mitogen-activated, ERK-activating kinase (MEK)1/2 inhibitor U0126. Coadministration of BPA (10(-12) to 10(-10) M) with 10(-10) M E(2) dose-dependently inhibited rapid E(2)-induced ERK1/2 activation in developing cerebellar neurons. The ability of BPA to act as a highly potent E(2) mimetic and to also disrupt the rapid actions of E(2) at very low concentrations during cerebellar development highlights the potential low-dose impact of xenoestrogens on the developing brain.