Diquat increases cysteine proteinase inhibitors greatly in rat plasma and tissues

The restriction of all minerals in the diet enhancing paraquat toxicity is regarded primarily as the shortage of Mg

This study compares the effect of the restriction of Mg with that of all-minerals in the diet on the toxicity of paraquat. To compare the severity of the toxicity, several biological values were examined; kininogen in plasma, thiobarbituric acid reactive substances in liver, Ca level in kidney, and Mg levels in liver and kidney. Osteogenic disorder Shionogi rats that cannot synthesize vitamin C like humans did not display paraquat symptoms after receiving minute amounts of paraquat dichloride, i.e. 125 ppm in the diet for 8 days, and those biological values remained the same as those of the control. Rats fed with Mg at half of the recommended amounts also did not show any changes in those levels. The dosage of 125 ppm paraquat under the restriction of Mg, however, induced paraquat intoxication and increased those levels greatly. This result arises a question whether the intoxication is due to the imbalance of Ca and Mg or due to the shortage of Mg itself, because imbalance of Ca and Mg sometimes induces more serious effects than the shortage of Mg itself. Therefore, we fed rats an all-mineral restricted diet where the balance of Ca and Mg was maintained. The dosage of paraquat under all-mineral restriction, however, induced much more serious intoxication than that under Mg restriction. In conclusion, the shortage of Mg itself seems to be responsible for the induction of paraquat intoxication.

Determination of genotoxicity of the metabolites of the pesticides Guthion, Sencor, Lorox, Reglone, Daconil and Admire by 32P-postlabeling

Commercial formulations of the pesticides: Guthion (azinphos methyl), Sencor (metribuzin), Lorox (linuron), Reglone (diquat), Daconil (chlorothalonil) and Admire (imidacloprid) were studied for their genotoxicity by 32P-postlabeling. Metabolites of the pesticides were obtained enzymatically using arochlor induced rat liver S9 fraction, in an NADPH generating system. The resulting metabolites were reacted with calf thymus DNA and the DNA was analyzed for presence of adducts by either the nuclease P1 or butanol enrichment. Nuclease P1 enrichment resulted in adducts for all the pesticides. Compared to the level of adducts in control DNA, the levels in pesticide-treated DNA were higher for all the pesticides, except Daconil. The increase in adduct numbers for pesticide-treated DNAs ranged from 4.9-12.4 times the control-DNA indicating pesticide genotoxicity in this in vitro system. Enrichment using butanol extraction gave three adducts unique to Sencor-DNA. These adducts were different from those obtained with nuclease P1 enrichment of the same. B(alpha)P was the positive control for the in vitro metabolism, and two adduct enrichment procedures: nuclease P1 digestion and butanol extraction.

Effect of dietary paraquat on a rat mutant unable to synthesize ascorbic acid

To obtain some insight into the toxicity of paraquat (PQ) in humans, PQ dichloride at 250 ppm in the diet was administered to both normal (NO) rats and ODS-od/od (OD) rats which are unable to synthesize ascorbic acid (AsA). Firstly, OD rats and NO rats treated with PQ were compared with untreated NO rats (CO). Only OD rats displayed several symptoms of PQ poisoning such as anorexia, hypokinesia, diarrhea, epistaxis, tremor and their pili became rough about 9 days after. Their cysteine proteinase inhibitor level in plasma and lung increased to 2- and 6-fold, respectively, of CO. In contrast, NO rats treated with PQ resembled CO rats, and their cysteine proteinase inhibitor levels were unchanged until 11 days. After this period they began to display symptoms. Secondly, OD rats fed with different amounts of AsA were compared. Excess AsA delayed the onset of symptoms by only 1 day. Thirdly, the day of onset of symptoms was found to be influenced with the weight of rats.