Impact of e-cigarette refill liquid exposure on rat kidney

Electronic-cigarettes (e-cigarette), the alternative to classic cigarettes are becoming extremely popular but their safety is not still established. Recent studies have showed cytotoxic effects of the electronic cigarette and its recharge e-liquid, in vitro. The present study was designed to evaluate e-cigarette liquid nephrotoxicity in rats. For this purpose, 32 rats were treated for 28 days as follows: Control group was injected intraperitoneally with NaCl 9 g/l; e-cigarette 0% treated group received an intraperitoneal injection of e-liquid without nicotine diluted in NaCl 9 g/l, e-cigarette treated group, received an intraperitoneal injection of e-liquid containing 0.5 mg of nicotine/kg of body weight/day diluted in NaCl 9 g/l and nicotine-treated group received an intraperitoneal injection of 0.5 mg of nicotine/kg of body weight/day diluted in NaCl 9 g/l. In nicotine group, creatinine level was increased, whereas urea and acid uric levels were decreased. In e-liquid-exposed groups, levels of uric acid and mainly urea were lower. Interestingly, after e-liquid exposure, oxidative stress status showed increased total protein and sulfhydril content, whereas superoxide dismutase and catalase activities were decreased. However, the levels of lipid peroxides were not increased after e-liquid exposure. Histological studies identified excess of cells with reduced and dark nuclei exclusively located in the renal collecting ducts. Thus, e-liquid seems to alter anti-oxidant defense and to promote minor changes in renal function parameters. This preliminary study raises some flags about possible nephrotoxicity of e-cigarette liquids in rats. As some features observed in rats may not be observed in human smokers, additional studies are needed to further qualify conclusions that might be applicable to actual users of e-cigarettes.