De Flora S, Badolati G S, Serra D, Picciotto A, Magnolia M R, Savarino V
Institute of Hygiene, School of Medicine, University of Genoa, Italy.
Mutat Res. 1987 Nov;192(3):169-74. doi: 10.1016/0165-7992(87)90051-0.
Samples of gastric juice from variously treated subjects efficiently reduced hexavalent chromium and decreased its mutagenicity. Chromium reduction was due to thermostable components of gastric secretions and was favoured by the acidity of the intragastric environment. The circadian monitoring of pH and of chromium reduction, as assessed by colorimetric analysis at hourly intervals, showed a basal activity (less than 10 micrograms/ml gastric juice) during the night and interdigestive periods, and peaks (tens of micrograms/ml) during the 3-4-h periods after each meal. Assays in the Ames reversion test confirmed that the decrease in mutagenicity of sodium dichromate produced by gastric juice was significantly enhanced after meals. This physiological mechanism is expected to provide an important protective barrier against the oral toxicity of this metal, and may explain its lack of oral carcinogenicity.
来自不同处理对象的胃液样本能有效还原六价铬并降低其致突变性。铬的还原归因于胃分泌物中的热稳定成分，且胃内环境的酸性有利于此过程。通过每小时进行比色分析评估的pH值和铬还原的昼夜监测显示，夜间和消化间期有基础活性（胃液中低于10微克/毫升），而每餐饭后3 - 4小时出现峰值（数十微克/毫升）。艾姆斯回复突变试验证实，胃液使重铬酸钠致突变性降低的作用在饭后显著增强。这种生理机制有望为抵御这种金属的口服毒性提供重要的保护屏障，并且可能解释其缺乏口服致癌性的原因。
