Effects of γ-irradiation on Na,K-ATPase in cardiac sarcolemma
| Autor: | Miroslav Barancik, Jana Vlkovicova, Norbert Vrbjar, Marko Fülöp, Barbora Kalocayova, Jan Slezak, Pavel Babal, V. Jendruchová, Pavol Janega, Lucia Mézešová |
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| Rok vydání: | 2013 |
| Předmět: |
Male
Antioxidant medicine.medical_treatment Clinical Biochemistry chemistry.chemical_element Blood Pressure Oxygen Sarcolemma Neoplasms medicine Animals Enzyme kinetics Na+/K+-ATPase Rats Wistar Molecular Biology biology Hypertrophy Right Ventricular Chemistry Myocardium Substrate (chemistry) Heart Cell Biology General Medicine Enzyme assay Rats Biochemistry Gamma Rays Hypertension Biophysics biology.protein Hypertrophy Left Ventricular Sodium-Potassium-Exchanging ATPase Reactive Oxygen Species Intracellular |
| Zdroj: | Molecular and cellular biochemistry. 388(1-2) |
| ISSN: | 1573-4919 |
| Popis: | Previous studies showed that adverse effect of ionizing radiation on the cardiovascular system is beside other factors mostly mediated by reactive oxygen and nitrogen species, which deplete antioxidant stores. One of the structures highly sensitive to radicals is the Na,K-ATPase the main system responsible for extrusion of superfluous Na+ out of the cell which utilizes the energy derived from ATP. The aim of present study was the investigation of functional properties of cardiac Na,K-ATPase in 20-week-old male rats 6 weeks after γ-irradiation by a dose 25 Gy (IR). Irradiation induced decrease of systolic blood pressure from 133 in controls to 85 mmHg in IR group together with hypertrophy of right ventricle (RV) and hypotrophy of left ventricle (LV). When activating the cardiac Na,K-ATPase with substrate, its activity was lower in IR in the whole concentration range of ATP. Evaluation of kinetic parameters revealed a decrease of the maximum velocity (V max) by 40 % with no changes in the value of Michaelis–Menten constant (K m). During activation with Na+, we observed a decrease of the enzyme activity in hearts from IR at all tested Na+ concentrations. The value of V max decreased by 38 %, and the concentration of Na+ that gives half maximal reaction velocity (K Na) increased by 62 %. This impairment in the affinity of the Na+-binding site together with decreased number of active Na,K-ATPase molecules, as indicated by lowered V max values, are probably responsible for the deteriorated efflux of the excessive Na+ from the intracellular space in hearts of irradiated rats. |
| Databáze: | OpenAIRE |
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