Author
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Uthus, Eric |
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Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only Publication Acceptance Date: 4/6/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Recent findings suggest that arsenic (As) has a physiological role affecting methionine (Meth) cycling but its specific site of action is unknown. Meth cycling involves the remethylation of homocysteine to Meth by BHMT (which uses a methyl group derived from choline) or Meth synthase (which uses a methyl group derived from FA). To further study the effects of As on Meth cycling, and especially on BHMT, a 2x2x2 factorially arranged experiment that used male weanling Sprague-Dawley rats fed an amino acid-based diet was designed. Dietary variables were As (0 or 0.5 ug/g); amino acid, either DL-Meth (47 mmol/kg) or DL-homocystine (Hcys, 23.5 mmol/kg); and vitamin, either choline (2.5 g bitartrate/kg) or folic acid (FA, 4 mg/kg). All rats received 10 g succinylsulfathiazole/kg diet. After 54 days an interaction between As and vitamin affected the liver activity of BHMT. Arsenic deprivation did not affect the activity of BHMT T in rats fed FA. However, in rats fed choline, the activity of BHMT was significantly (p<0.001) decreased by As deprivation, regardless of amino acid. Liver BHMT (mean +/- SE, N=5* or 6/group), nmol/min/mg protein: Hcys+FA Meth+FA Hcys+choline Meth+choline 0 As 0.146+/-0.016* 0.355+/-0.033 0.215+/-0.029 0.290+/-0.045 0.5 As 0.120+/-0.017* 0.317+/-0.033 0.329+/-0.024 0.442+/-0.049* These findings suggest that As has a role in Meth cycling involving BHMT. |
