RESUMO
The relationship between the development of porphyria and free-radical formation induced by hexachlorobenzene was studied in iron-overloaded rats. The first sign of porphyria, an increase in porphyrins in the liver, was detected at day 22. Liver malondialdehyde was also increased at day 22. During the following weeks, liver porphyrins and malondialdehyde increased simultaneously, accompanied by a decrease in uroporphyrinogen decarboxylase activity and glucose-6-phosphate activity in liver, and a high excretion of porphyrins in the urine. In the rats given hexachlorobenzene, changes were detected in the pattern of lipids in the liver microsomes. In comparison with the controls, there were decreases in C20:4 and C22:5 fatty acids, whereas the fatty acid C20:3w6 was increased. In this study of hexachlorobenzene-induced liver damage there was no difference in the time course of the development of porphyria and that of lipid peroxidation.
Assuntos
Clorobenzenos/toxicidade , Hexaclorobenzeno/toxicidade , Peroxidação de Lipídeos , Porfirias/induzido quimicamente , Animais , Ácidos Graxos/análise , Feminino , Radicais Livres , Fígado/análise , Fígado/enzimologia , Microssomos Hepáticos/análise , Porfirias/etiologia , Porfirinas/análise , Porfirinas/urina , Ratos , Ratos Endogâmicos , Fatores de Tempo , Uroporfirinogênio Descarboxilase/análiseRESUMO
We present a modification of the HemoQuant assay, a good but lengthy and tedious method for determining heme in feces by means of its transformation to porphyrins. The laborious extraction procedure was replaced by a simple centrifugation procedure. The nonhomogeneous hot oxalic acid suspension was replaced by acetic acid. We observed no significant difference in results between samples analyzed by the older method vs the present modification (r = 0.996, n = 52). Mean (and SD) analytical recoveries of added hemoglobin and protoporphyrin were 99% (7%) and 93% (6%), respectively. The analytical procedure can now be automated by using discrete samplers and a flow-through fluorometer. Initial sampling and dilution of feces are still done manually, however. The excellent specificity, sensitivity, and overall analytical performance of the original method are retained, while circumventing the practical inconveniences of this reliable screening test for occult blood in feces.
