Kinetic studies of the Na+-K+-ATPase enzyme system in brain and heart of aging rats
| Autor: | M. S. Liu, Philip W. Landfield, L. B. Poole |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
Male
medicine.medical_specialty Aging Physiology ATPase Ouabain Physiology (medical) Internal medicine medicine Animals Na+/K+-ATPase chemistry.chemical_classification 4-Nitrophenylphosphatase biology Myocardium Brain Metabolism Enzyme assay Rats Inbred F344 Rats Enzyme Activation Kinetics Thyroxine Enzyme Endocrinology chemistry biology.protein Potassium Triphosphatase Sodium-Potassium-Exchanging ATPase Hormone medicine.drug |
| Zdroj: | The American journal of physiology. 247(5 Pt 2) |
| ISSN: | 0002-9513 |
| Popis: | Kinetic analyses of the Na+-K+-adenosine triphosphatase (ATPase) system were performed in brain and heart preparations from young mature (4 mo old) and healthy aged (25 mo old) rats. The K+-activated p-nitrophenylphosphatase (K+-pNPPase) method was used to assess activity of the enzyme system. Ouabain inhibition of K+-pNPPase activity was also examined. A significant age-related decrease in maximal velocity (Vmax) was found in cardiac K+-pNPPase activity, but no changes were seen in the K+ concentration for half-maximal velocity (K0.5). No age differences in Vmax or K0.5 were seen for brain. No differences in ouabain inhibition were found in either brain or heart. In a second experiment, the major component of the age-related decline in cardiac K+-pNPPase activity was found to occur between 5 and 14 mo of age, a period during which plasma thyroxine had previously been found to decline in the same animals. Since peripheral Na+-K+-ATPase activity is partly thyroid hormone dependent, the age-dependent decrease in cardiac enzyme activity appears to be secondary to neuroendocrine changes. |
| Databáze: | OpenAIRE |
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