Hydrocortisone-mediated changes in the concentration of tyrosine transaminase in rat liver: an immunochemical study |
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| Authors: | I B Levitan T E Webb |
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| Affiliation: | 1. Department of Clinical Veterinary Studies, Faculty of Veterinary Science, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe;2. Laboratory of Epidemiology, Biostatistics and Animal Health Economics, Faculty of Veterinary Medicine, University of Thessaly, Karditsa, 224 Trikalon St., Greece;3. Botswana National Veterinary Laboratory, Private Bag 0035, Gaborone, Botswana;4. Department of Paraclinical Veterinary Studies, Faculty of Veterinary Science, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabwe;1. Departments of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan;2. Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan;3. Graduate Institute of Clinical Medical Science, Chang Gung University School of Medicine, Taoyuan, Taiwan;4. Biostatistics Consulting Center and Department of Public Health, Chang Gung University School of Medicine, Taoyuan, Taiwan;5. Department of Pediatrics, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan;6. Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan;7. Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan;1. Division of Nephrology and Hypertension, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany;2. Department of Medicine, Division of General Internal and Emergency Medicine, Nephrology, and Rheumatology, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany;3. Institute of Intensive Care Medicine, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland;4. Division of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany;1. Instituto de Investigación de la Cadena Láctea (INTA-CONICET), Estación Experimental Agropecuaria Rafaela, Ruta 34, km 227, CP 2300 Rafaela, Santa Fe, Argentina;2. Laboratorio de Referencia de la OIE para Brucelosis, Dirección General de Laboratorio y Control Técnico (DiLab), Servicio Nacional de Sanidad y Calidad Agroalimentaria (SENASA), Martínez CP 1640, Buenos Aires, Argentina |
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| Abstract: | By standard immunochemical techniques, with a specific antiserum against purified hepatic tyrosine transaminase, it has been shown that the degradation of this enzyme in the livers of adrenalectomized rats is totally eliminated between one and four hours after the administration of an optimum inducing dose of hydrocortisone (i.e. during the initial phase of the induction cycle when the rate of enzyme synthesis increases 4- to 5-fold over the basal value). An immunochemical analysis of the second phase of the induction cycle (i.e. the fall in enzyme activity which begins approximately 5.5 hours after the initiation of induction) indicates that the rate of enzyme synthesis returns to the basal level during this period; the drop to the basal rate occurs within seven, hours after the administration of the corticosteroid. Immunochemical measurements were also employed to study the nature of the effects of several inhibitors of protein biosynthesis on the induced enzyme. The results indicate that the maintenance of the tyrosine transaminase activity at or near the induced level by 8-azaguanine, 5-azacytidine or cycloheximide results from a failure to re-initiate the degradation of the enzyme. |
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