“Pod‐based” e‐cigarettes such as JUUL are currently the most prevalent electronic nicotine delivery systems (ENDS) in the United States. JUUL‐type ENDS utilize nicotine salts protonated with benzoic acid rather than freebase nicotine. However, limited information is available on the cellular effects of these products. Cytoplasmic Ca²⁺ is a universal second messenger that controls many cellular functions including cell growth and cell death. Of note, dysregulation of cell Ca²⁺ homeostasis has been linked with several disease processes including autoimmune disease and several types of cancer. We exposed HEK293T cells and THP‐1 macrophage‐like cells to different JUUL e‐liquids. We evaluated their effects on cellular viability and Ca²⁺ signaling by measuring fluorescence from calcein‐AM/propidium iodide and Fluo‐4, respectively. E‐liquid autofluorescence was used to look for e‐liquid permeation into cells. To identify the mechanisms behind the Ca²⁺ responses, different inhibitors of Ca²⁺ channels and phospholipase C signaling were used. JUUL e‐liquids caused significant cytotoxic effects, with “Mint” flavor being the most cytotoxic. The Mint flavored e‐liquid also caused a significant elevation in cytoplasmic Ca²⁺. Using autofluorescence, the permeation of JUUL e‐liquids into live cells was confirmed, indicating that intracellular organelles are directly exposed to e‐liquids. Further studies identified the endoplasmic reticulum as being the source of e‐liquid‐induced changes in cytoplasmic Ca²⁺. Nicotine salt‐based e‐liquids cause cytotoxicity and elevate cytoplasmic Ca²⁺, indicating that they can exert biological effects beyond what would be expected with nicotine alone. These effects are flavor‐dependent, and we propose that flavored e‐liquids be reassessed for potential lung toxicity.

中文翻译：

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含尼古丁盐的电子烟液对细胞的影响

“基于豆荚的”电子烟，例如 JUUL，是目前美国最流行的电子尼古丁传递系统 (ENDS)。JUUL 型 ENDS 利用苯甲酸质子化的尼古丁盐，而不是游离碱尼古丁。然而，关于这些产品的细胞作用的信息有限。细胞质 Ca ²⁺是一种通用的第二信使，可控制许多细胞功能，包括细胞生长和细胞死亡。值得注意的是，细胞 Ca ²⁺稳态失调与多种疾病过程有关，包括自身免疫性疾病和多种类型的癌症。我们将 HEK293T 细胞和 THP-1 巨噬细胞样细胞暴露于不同的 JUUL 电子液体中。我们评估了它们对细胞活力和 Ca ^{2+ 的影响}通过分别测量钙黄绿素-AM/碘化丙啶和Fluo-4 的荧光信号。电子液体自发荧光用于寻找电子液体渗透到细胞中。为了确定 Ca ²⁺反应背后的机制，使用了不同的 Ca ²⁺通道抑制剂和磷脂酶 C 信号传导。JUUL 电子烟液引起了显着的细胞毒性作用，其中“薄荷”味是最具细胞毒性的。薄荷味的烟油也导致细胞质 Ca ²⁺显着升高. 使用自发荧光，证实了 JUUL 电子液体渗透到活细胞中，表明细胞内细胞器直接暴露于电子液体中。进一步的研究确定内质网是电子液体诱导的细胞质 Ca ²⁺变化的来源。基于尼古丁盐的电子烟液会引起细胞毒性并升高细胞质 Ca ²⁺，表明它们可以发挥超出单独使用尼古丁预期的生物效应。这些影响取决于风味，我们建议重新评估调味电子液体的潜在肺毒性。