Elusidation of the enhancing factor in paraquat toxicity under magnesium restriction

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A highly sensitive but simple method for the quantification of Cu was devised (published in Clin Chem, 2001, JpnJ Forensic Toxicol, 2001). Only 5μl of plasma or 1.5 ml of running water is enough to quantify Cu. By use of this method tissue Cu levels of rats intoxicated with paraquat at 250 ppm in the diet were examined. The contents of Fe, Mg and Zn were determined by atomic absorption spectrometry, Shimadsu AA-6200 which was obtained by the present Grant-in-Aid. In intoxicated rats, Cu increased 2-fold of the control in lung, liver or plasma, and decreased to 0.5-foldin kidney. Fe increased 2-fold in liver or spleen, and decreased to 0.5-fold in plasma. Mg increased 2-fold in kidney. Liver Mg or Zn increased significantly (J Toxicol Environ Health, 2002)Mg restricted rats dosed with 125 ppm paraquat gave the same changes in these minerals (JpnJ Legal Med, 2001). However, Ca in kidney increased 10-foldin Mg restricted rats (will be reportedinThe86th Congress ofJpn Soc Legal Med, 2002). Usually it takes more than 35days to accumulate Ca at such a high level by dietary Mg restriction only. Feeding paraquat at 125 ppm under Mg restriction accelerated both paraquat toxicosis and Mg deficiency. The kidney Ca of rats fed with 125 ppm paraquat under all mineral restriction increased to 20-fold, where the ratio of Ca to Mg in the diet was maintained (will be reported in ISALM, 2002).