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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 9/30/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: In the 1970s,studies done on rats, showed that arsenic deprivation increased perinatal mortality and depressed growth of surviving pups. Initial studies with chicks used diets high in arginine to see if this would amplify any changes caused by arsenic deprivation. From these studies, it was concluded that arsenic was affecting some metabolic pathway which also was affected by zinc nutriture, and it most likely was one involving arginine metabolism. Studies where dietary arginine, arsenic and zinc were varied and resulted in the hypothesis that arsenic, arginine and zinc were interacting to affect the amount of arginine being shunted through the pathway that converted arginine to urea and ornithine; attention was focused on the pathway in which arginine is converted to guanidoacetic acid and subsequently methylated by S-adenosylmethionine. Thus, the effect of arsenic deprivation on methionine and methyl metabolism was examined. These studies indicated that arsenic is of physiologic importance when methionine metabolism is stressed and that low intakes of arsenic apparently results in impaired methyl metabolism, and a reduction in S-adenosylmethionine which is used to methylate critical substances such as the bases of nucleic acids and homocysteine. These alterations could lead to DNA hypomethylation which has been associated with an increased incidence in some forms of cancer, and increased plasma homocysteine which has been associated with an increased incidence of cardiovascular disease. In other words, a low intake of arsenic could be just as harmful as a high intake. Thus, regulatory groups involved in setting toxicological standards should accept the fact that there are beneficial intakes of arsenic. |
