In Vitro Toxicity of Gallium Arsenide in Alveolar Macrophages Evaluated by Magnetometry, Cytochemistry and Morpholegy.

Abstract

Gallium arsenide (GaAs), a chemical compound of gallium and arsenic, causes various toxic effects including pulmonary diseases in animals. Since the toxicity is not completely investigated, GaAs has been used in workplaces as the material of various semiconductor products. The present study was conducted to clarify the toxicity of GaAs particles in the alveolar macrophages of hamsters using magnetometry, enzyme release assays and morphological examinations. Alveolar macrophages obtained from hamsters by tracheobronchial lavage and adhered to the disks in the bottom of wells were exposed to ferrosoferric oxide and GaAs particles. Ferrosoferric oxide particles were magnetized externally and the remanent magnetic field was measured. Relaxation, a fast decline of the remanent magnetic fields radiated from the alveolar macrophages, was delayed and decay constants were decreased dose-dependently due to exposure to GaAs. Because the relaxation is thought to be associated with cytoskeleton, the exposure of GaAs may have impaired the motor function of them. Enzyme release assay and morphological findings indicated the damage to the macrophages. Thus the cytotoxicity causes cytostructural changes and cell death. According to DNA electrophoresis and the TUNEL method, necrotic changes occur more frequently than apoptotic changes.

Magnetometric evaluation of toxicities of chemicals to the lungs and cells

“…LDH release was increased in GaAsexposed cells. According to DNA electrophoresis and the TUNEL method, apoptotic changes failed to be detected [3]. Because AsCl 3 alone caused effects identical to those of GaAs on magnetometry and LDH release in macrophages, and Ga 2 O 3 did not show significant effects, it was concluded that As was responsible for the toxicity to macrophages [22].…”

“…Iron oxide particles with a mean geometric diameter of 0.26 lm were used as the magnetometric index. Male hamsters [2,3] or F344/NS1c rats [20] were anesthetized and bronchoalveolar lavage fluid was obtained. The harvested cells, about six million cells, were divided into two groups: one group was exposed to different doses of chemicals, and the other group was exposed to phosphate-buffered saline as a control.…”

“…Macrophages that adhered to glass were used for observation by scanning electron microscopy and transmission electron microscopy. Apoptosis was evaluated by both the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method and the DNA ladder method [3]. The DNA ladder method was performed in two steps, DNA extraction and agarose gel electrophoresis.…”

“…We evaluated the cytotoxic effects of the following chemicals, particles, and fibrous materials as compounds [3,22,23], cadmium (Cd) compounds [24,25], silica [26] or other dust, chryosotile fibers (CFs) [2], and five manmade mineral fibers (MMMFs) [4,5], using the abovementioned tests, and the results are shown in Table 1. On the basis of magnetometry and the LDH release assay, we estimated that there were no observable adverse effect levels (NOAEL) on the cells.…”

“…Therefore, AMs have been used for the in vitro evaluation of the toxic effects of chemicals. Using the rate of relaxation as an indicator of the cytoskeletal function of cells by magnetometry, we have found several chemicals affecting relaxation [1][2][3][4][5]. The magnetometric measurement of lung contamination of magnetite was developed by Cohen [6].…”