RESUMO
The clearance of gamma-glutamyltransferase was studied by injecting the purified human liver enzyme intravenously in the rat. The results show a biphasic clearance, with a rapid initial rate of removal. The initial uptake is more rapid for neuraminidase-treated GT. Liver accounts for the bulk organ uptake and the enzyme is almost exclusively taken up into the parenchymal cells. We suggest that the uptake of circulating GT is receptor mediated, most likely by the galactose receptor of the parenchymal cells.
Assuntos
Fígado/enzimologia , gama-Glutamiltransferase/farmacocinética , Animais , Humanos , Injeções Intravenosas , Radioisótopos do Iodo , Cinética , Masculino , Taxa de Depuração Metabólica , Neuraminidase/farmacologia , Ratos , Ratos Endogâmicos , Receptores de Superfície Celular/metabolismo , Distribuição Tecidual , gama-Glutamiltransferase/administração & dosagemRESUMO
The mitochondrial isoenzyme of aspartate aminotransferase showed only slight increases in serum of twenty-seven patients after uncomplicated coronary bypass surgery, which contrasted the rapid and substantial increases in creatine kinase MB. In seven patients suffering perioperative infarction or serious complications, substantial increases in mitochondrial aspartate aminotransferase were detected and the elevations in creatine kinase MB were prolonged. Mitochondrial aspartate aminotransferase may appear as a specific marker of myocardial necrosis following coronary bypass surgery. The elevations of creatine kinase and creatine kinase MB were detected as early as 5 minutes after onset of coronary reperfusion and slightly higher activities were measured in coronary sinus blood than in systemic blood sampled simultaneously. Increases in mitochondrial aspartate aminotransferase, however, could first be measured 8 hours after reperfusion.
Assuntos
Aspartato Aminotransferases/sangue , Ponte de Artéria Coronária/efeitos adversos , Creatina Quinase/sangue , Isoenzimas/sangue , Mitocôndrias Cardíacas/enzimologia , Eletrocardiografia , Feminino , Humanos , Cinética , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/etiologiaRESUMO
Several multiple forms of gamma-glutamyltransferase (EC 2.3.2.2) have been described in serum. Most of these are large complexes between the enzyme and circulating lipoproteins. One dominating form is complexed with high-density lipoprotein; a small, hydrophilic form is present in minor amounts. We purified the two forms by immunoaffinity chromatography, injected the purified forms into rabbits, and studied the clearance of the two forms by measuring the change in enzyme activity and in enzyme protein concentration with an enzyme-linked immunosorbent assay. The half-life of the hydrophilic enzyme was 9 h; that of the lipoprotein-enzyme complex was 20 h. This indicates that the lipoprotein-enzyme complex accumulates in serum relative to the hydrophilic enzyme, suggesting in part an explanation of the dominance of the larger form in disease.
Assuntos
Hepatopatias/enzimologia , gama-Glutamiltransferase/sangue , Animais , Ensaio de Imunoadsorção Enzimática , Meia-Vida , Humanos , Lipoproteínas HDL/sangue , Hepatopatias/sangue , Taxa de Depuração Metabólica , Tamanho da Partícula , Coelhos , gama-Glutamiltransferase/farmacocinéticaRESUMO
We describe an improved separation of the isoenzymes of aspartate aminotransferase (EC 2.6.1.1), based on ion-exchange chromatography. Involving the "Fast Protein Liquid Chromatography" system (Pharmacia) with a MonoQ column, this rapid, reproducible method for quantifying the mitochondrial enzyme shows good resolution and sensitivity, and results correlate well with those by an established immunochemical method.