Systematic identification of cardiotoxic e-cigarette flavorants

摘要 自2003年首次引入电子烟以来，电子烟(e-cig)的使用大幅增加。电子烟 设备将电子液体雾化，这些液体通常由含有不同水平的尼古丁和调味剂的保湿剂组成 化学制品。尽管有数以千计的商业风味混合物，但它们通常重叠在 单独的风味化学品(调味剂)，数量要少得多。这些调味料中的许多都属于 这是一种常见的化学物质，通常被认为可以安全摄入。然而，他们的直接和间接 加热和吸入后对心脏的影响，特别是与尼古丁结合在一起，大多数情况下仍不清楚。 仅直接接触尼古丁就会明显影响心脏动作电位波形，这可能会导致 由于吸烟者心律失常和心脏性猝死的发生率很高。最近的证据也表明 电子烟中的尼古丁也可能同样会导致不良的心脏后果。然而，调味剂对食品的影响 E-cig气雾剂对心脏的影响仍未得到测试。在我们正在进行的研究中，我们发现接触尼古丁- 含有各种口味的e-cig气雾剂，显著和不同地改变了小鼠的心电图， 不同程度地引起QT间期延长，心率加快，并诱发心律失常。同样，两个独立的 具有相同特征的香料的E-液体持续增加室性心律失常。此外，我们 在心肌细胞中观察到，用e-cigs常见的几种调味剂治疗直接改变了心肌的收缩能力， 节律性和动作电位时程。然而，目前还不清楚电子烟中的个别调味剂是如何 气雾剂在体内对心脏有直接或间接的影响。考虑到电子烟越来越受欢迎， 迫切需要研究这些产品中成分的体内毒理学特征，我们建议测试 电子烟香料改善电子烟烟雾暴露对心脏影响的假说 电生理学，导致心律失常和心脏功能重塑。为了测试这一点，我们将 系统地识别香料暴露对心脏电生理的急性和长期影响 结合了体内、体外和体外最先进的方法。具体来说，我们将：1)确定 加味电子烟雾化吸入对在体心脏电生理的急性影响，2)检测 香料在体外和体外对心脏电生理的直接影响，以及，3)阐明有害的 急性和慢性香料气雾剂暴露对心脏电生理、结构和功能的影响 功能。这些研究响应了FDA/CTP的研究重点，将提供新的数据 展示了不同风味的化学物质如何影响心脏的兴奋性，并潜在地促进心律失常的发生。 这些结果将有助于制定政策，规范调味品的生产、分销和营销 电子烟。

Abstract The use of e-cigarettes (e-cigs) has increased substantially since they were first introduced in 2003. E-cig devices aerosolize e-liquids that typically consist of humectants with variable levels of nicotine and flavoring chemicals. Although there are thousands of commercially available flavor mixtures, they routinely overlap in individual flavor chemicals (flavorants), which are far fewer in number. Many of these flavorants belong to common chemical classes and are generally recognized as safe for ingestion. However, their direct and indirect cardiac effects following heating and inhalation, particularly in combination with nicotine, remain mostly unknown. Direct exposure to nicotine alone distinctly affects the cardiac action potential waveform, potentially contributing to the high incidence of arrhythmias and sudden cardiac death among smokers. Recent evidence also suggests that nicotine in e-cigs may similarly promote adverse cardiac outcomes. Yet, the influence of flavorants on the cardiac effects of e-cig aerosols remains untested. In our ongoing work, we found that exposure to nicotine- containing e-cig aerosols of various flavors acutely and differentially altered the electrocardiogram (ECG) in mice, variably inducing QT interval prolongation, increasing heart rate, and evoking arrhythmia. As well, two separate e-liquids with the same characterizing flavorant consistently increased ventricular arrhythmias. Furthermore, we observed in cardiomyocytes that treatment with several flavorants common to e-cigs directly altered contractility, rhythmicity, and action potential duration. Nonetheless, it remains unknown how individual flavorants in e-cig aerosols exert direct or indirect cardiac effects in vivo. Considering the growing popularity of e-cigarettes and the urgent need for studying the in vivo toxicological profile of constituents in these products, we propose to test the hypothesis that e-cigarette flavorants modify the effects of e-cig aerosol exposures on cardiac electrophysiology, leading to arrhythmias and functional remodeling of the heart. To test this, we will systematically identify both acute and long-term effects of flavorant exposure on cardiac electrophysiology using a combination of state-of-the-art in vivo, in vitro, and ex vivo approaches. Specifically, we will: 1) Identify the acute effects of flavored e-cig aerosol inhalation on cardiac electrophysiology in vivo, 2) Examine the direct impact of flavorants on cardiac electrophysiology in vitro and ex vivo, and, 3) Elucidate deleterious impacts of acute and chronic flavorant aerosol exposure on cardiac electrophysiology, structure, and function. These studies, which are responsive to the research priorities of the FDA/CTP, will provide new data showing how different flavor chemicals affect cardiac excitability and potentially promote arrhythmogenesis. Such results would aid in formulating policies regulating the manufacture, distribution and marketing of flavored e-cigarettes.