| Effects of Dopamine and Ephedrine on Na-K-ATPase Activity in the Red Cell Ghosts of Rabbits. |
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Sung Taik Park, Sae Jin Choi, Kwang Jin Kim |
1Department of Anesthesiology, College of Medicine, Chungnam National University, Taejeon, Korea.
2Department of Physiology, College of Medicine, Chungnam National University, Taejeon, Korea. |
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| Abstract |
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Na-K-ATPase, which is activated by Na+ and K+ at physiologic concentrations, is most abundantly present in tissues which have a high capacity for sodium and potassium transport, and the activity of this enxyme is specifically inhibilted by ouabain. Dopamine, isoproterenol, and ephedrine are the sympathomimetic agonists which are used widely in the clinical field as the therapeatic drugs for hypotension, bradycardia, and arrhythmiss produced by local anesthetics, and also for bronchospasm. This study attempted to investigate the effects of pH changes in the solution of Tris-HCI buffer and the effects of the above sympathomimetic drugs on the Na-K-ATPase activity of re cell ghosts, and to compare the effects of the drug actions in the absence or presence of giaseng extract. The red cell ghosts were purified by the method of Rosenberg and Guidotti, and the amount of the decomposed inorganic phosphorus to be the indicator of Na-K-ATPase activity at 37 degrees C was measured by the method of Fiske and Subbarow. And all the experimental processes were carried out at 44 degrees C(or ice). The results are summarized as follows: 1) The optimal pH of Na-K-ATPase activity was 7.4 and the activities of total ATPase were 1.2125+/-0.0388 and 0.5400+/-0.0135mM/G cells/hr, respectively. 2) The optimal pH did not change in the presence of ginseng extract, and the extract significantly increased the activity of Na-K-ATPase: the activities of total ATPased and Na-K-ATPase were 1.4560+/-0.0615 and 0.6505+/-0.0115mM/L cell/hr, respectively. 3) Dopamine and ephedrine specifically inhibited the Na-K-ATPases activity: The activities of total ATPase and Na-K-ATPase were 1.0505+/-0.0280 and 0.2340+/-0.0240 mM/L cells hr in dopamine 10 mg/ml, and 0.9155+/-0.0210 and 0.0955+/-0.0175mM/L cells/hr in ephedrine 4 mg/ml, respectively. 4) Isoproterenol had no effect on the ATPase activity in the presence or absence of ginseng extract. 5) Ginsang extract significantly decreased the inhibited degree of Na-K-ATPase and was 1.535+/-0.0250 an 1 0.3690+/-0.0415 mM/L celle/hr in dopamine 10mg/ml, and was 1.1075+/-0.0275 and 0.2095+/-0.0370 mM/L cells/hr in ephedrine 4 mg/ml, respectively. 6) Mg-ATPase did not have any effect in the presence of dopamine and ephedrine with or without ginseng extract. |
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