水銀中毒に関する研究 (Hg Series No 4) : 第2報 尿中水銀排泄に及ぼすチオクト酸(リポ酸)の効果

Abstract

Ueda et al. reported that Thioctic Acid (TA) had simmilar effect against mercury poisoning to that of BAL, and Ishii demonstrated that TA would combine with mercury to form hardly dissociable compounds which were excreted in the urine, both in vivo and vitro experiments. The tracer experiment which demonstrated that the presence of Hg might retard the excretion of TA labelled with S35 in the urine and the liver was presented in the part 1 of this paper by the author. In the present experiment, the effect of TA on urinary mercury excretion in the human body was investigated. Also differences in the effectiveness of TA against mercury poisoning were examined as to the routes of administration. The mount of mercury excreted in the urine was determined by the method of Natelson, partly modified by Ueda and Fujimura. The results obtained were as follows. 1) When rabbits in the state of sub-acute mercury poisoning were injected intramuscularly with 10 mg of TA, 24-hour urinary mercury excretion increased, but when administered by oral route no increase was found in all the cases. 2) When two healthy adult men were given intravenously 20 mg/day of TA, urinary mercury excretion increased two or three times that in the control period, whereas two cases orally administered with the same does showed no increase. 3) When five workers in a clinical thermoneter manufacturing factory received orally 30 mg/day of TA, in every case but one, a large amount of mercury was excreted in the urine, especially on the first day. And, when the administration was discontinued the excretion decreased. 4) Among five men who worked in the same factory in an environment with lower Hg vapor concentration, three showed an increase of mercury excretion with the oral administration of 60 mg/day of TA, and remaining two showed no change, compared with the control period before the administration. 5) When 3 men who were engaged in the operation of electric news board were given orally 60 mg/day of TA for 3 days, a slight increase of mercury excretion was observed only in one case. Summarizing the above results, it can be said that the parenteral administration of TA is effective for the excretion of mercury in the urine in man, and that there are large individual variations in the response to TA by oral route, the reason for which is open to further investigations.