Magnetometric Evaluation of Toxicity of Gallium Arsenide to Lungs and Alveolar Macrophage

砷化镓（GaAs）导致了光电器件如发光二极管和半导体激光器的发展。一些报告指出，肺部接触砷化镓粉尘是一种潜在的职业健康危害。已经研究了砷化镓暴露动物的体内肺毒性、免疫毒性和对卟啉代谢的影响。经气管内注入磁性颗粒对动物胸腔进行磁化后，磁场迅速下降，并被称为“松弛”。这一现象表明，由于巨噬细胞中被吞噬的氧化铁颗粒的随机旋转，肺部磁化后剩余磁场迅速减少。在第一部分的研究中，观察了砷化镓暴露家兔的延迟松弛和氧化铁的清除。在后一部分的研究中，将粘附在井底玻璃上的肺泡巨噬细胞暴露于氧化铁60mug（含或不含GaAs20mug/ml）培养基中。在GaAs自由介质中观察到快速弛豫，而在GaAs介质中观察到延迟弛豫。砷化镓对弛豫的影响呈剂量依赖性。由于在介质中加入Ga_2O_3对弛豫没有影响，可以认为砷对弛豫有影响。细胞LDH释放，经典的细胞毒性测试，也显示了GaAs对巨噬细胞的毒性作用。透射电镜显示砷化镓暴露后巨噬细胞的细胞膜、细胞器和细胞核发生了改变。体内细胞磁强计似乎适用于评价化学物质对吞噬细胞的毒性。

Gallium arsenide (GaAs) has led to the development of electro-optical devices such as light-emitting diodes and semiconductor lasers. Several reports point to pulmonary exposure to GaAs dust as a potential occupational health hazard. In vivo pulmonary toxicity, immuno toxicity and effects on porphyrin metabolism have been demons trated in animals exposed to GaAs.A rapid decrease in the magnetic field after magnetization of the thorax of animals intratracheally instilled with magnetic particles has been noted and designated as "relaxation". This phenomenon indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytosed iron oxide particles in macrophages. In the first part of study, delayd relaxation and clearance of iron oxide were observed in rabbits exposed to GaAs.In the latter part of study, alveolar macrophages adhered to glass in the bottom of wells were exposed to iron oxide 60mug with or without GaAs20mug/ml in culture medium. Rapid relaxation was observed in the sample of GaAs free medium, whereas relaxation for the specimen with GaAs was delayd. GaAs impaired relaxation dose-dependently. Since addition of Ga_2O_3 into the medium did not affect relaxation, arsenic is considered affecting relaxation.LDH release from cells, classical test for cellular toxicity, also indicated toxic effect of GaAs on macrophages. Transmission electron micros copy revealed alterations of cell membrane, organelles and nucleus in macrophages exposed to GaAs.In vivo cellular magnetometry appears applicable to evaluate toxicity of chemical substance on phagocytic cells.