ヒ素化合物の生体内動向について
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概要
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Accumulations of and excretions of arsenic in rats where the arsenic is administered continuously over long periods of time has as yet been left for study. This is because methods to measure trace amounts of arsenic in biological sample have not been well established. This author has reported on an accurate and highly sensitive new method to determine arsenic levels in biological samples which involves flameless atomic absorption spectrometry using a carbon tube atomizer. In order to measure arsenic accumulations and excretions in rats organs, the above method was applied to appropriate biological specimens. As a result, arsenic levels were measured.Procedure: One hundred and five male Wister rats weighing 80±1g were divided into four groups, five rats to a cage. Arsenic was in all cases administered as a single daily dose per os with catheter, and three groups (75 rats) were administered solutions of sodium arsenite amounting to either 10μgAs, 50μgAs or 100μgAs/day continuously for 100 days. The fourth group (30 rats) served as the control. For the determination of arsenic concentrations in rats organs, five rats from each group were sacrified at days 0 (control group only), 20, 40, 60, 80 and 100. And the amounts of arsenic excreted in the feces and urine were checked between every third and fourth day.Result: 1. The amounts of arsenic excreted in the urine of control rats showed a constant level of about 30% of ingested total arsenic (contained naturally in a standard diet). The group administered 10μgAs/day arsenic excreted 13% of the administered arsenic which increased to 25% as the duration of administrations increased. The groups administered 50μgAs/day and 100μgAs/day excreted from 5 to 15% of the administered arsenic.2. The amount of arsenic excreted in feces of control rats was almost equal to that in urine (approximately 30%). At early stage, rats administered arsenic excreted lesser amounts of arsenic (approximately 17∼22%) than the controls (approximately 30%). However, arsenic excretion ratios increased to about 30% as the period extended. These results are shown in Table 4.3. The average arsenic level in the whole blood of the controls at day 0 was 1.8ppm, increasing to 7.8ppm after 100 days. Most of the arsenic in blood is absorbed by erythrocytes. After arsenic was administered, it accumulated in blood at high levels. The concentrations of arsenic in blood was higher for subjects than for controls (Table 5).4. Arsenic accumulations in rats organs were obsereved for both subject and control groups rats except in the case of the skull of the 10μgAs/day and control groups. High concentrations of arsenic in the lungs, heart, kidneys, spleen, liver, testes, brain, muscles, skull and the hair from the experimental group were found when compared to those of control. The spleen, liver, kidneys and the lungs showed the highest concentrations of arsenic of all examined viscera.5. There were high correlations between arsenic concentrations in body hair and in viscera. Therefore, viscera arsenic concentrations may be hypothesized by examining the levels found in body hair alone (Table 11).
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