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KMID : 0377519810060040501
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Chung-Ang Journal of Medicine
1981 Volume.6 No. 4 p.501 ~ p.509
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Na^+K^+ ATPase Activity following Experimental Spinal Cord Injury
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Kim Kwan-Sik
Rhim Kwang-Seh
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Abstract
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The pathophysiology of spinal cord injuries are still obscure. Since 1972 Osterholm and Mathews expressed their cathecholamine theory in which the increased norepinephrine may cause hemorrhagic necrosis in the experimental spinal cord injury. The theory has been criticized by a number of investigators. There have been many convincing reports that Na^+K^+ ATPase plays an important role as a sodium pump to transport the Na ions and K ions across the cell membrane. This membrane bound enzyme was measured at the four level of the spinal cord following an impact injury as a part of an attempt to define the sequence of major cellular alteration. Fifty rabbits were used as experimental animals and divided into two groups; a group of cord trauma alone and the other group of cord trauma with administration of dexamethasone injection one hour prior to the impact injury. The activities of Na^+K^+ ATPase and Mg^++ ATPase were measured by the method of Kang and Lee(I976) at intervals of 5,15,30 and 60 minutes in four sites of the spinal cord (C_1, T_6,T_8,T_12) following impact injury of 400 gm-cm force to the T_6 level. The results were as follows; 1. The maximum value of the Na^Z++K^++ ATPase was obtained from the incubation medium containing 100 mM NaCl, 10 mM KCl and 3 mM MgCl_2 at 37℃ and pH 7.4. The ouabain above 10^-3M concentration inhibited the production of Na^+K^+ ATPase completely. 2. The mean values of Na^+K^+ ATPase and Mg^++ ATPase in the normal spinal cord of the rabbit were 4.14 and 3.47μ mole/mg protein/hr respectively. The Mg^++ ATPase represented about 46.6% of the total ATPase. 3. The significant fall in Na^+K^+ ATPase activity and slight fall in the Mg^++ ATPase activity were found in the group of trauma alone. 4. The mean values of Na^+K^+ ATPase and Mg^++ ATPase in the spinal cord of rabbit which had injection of dexamethasone before one hour of injury were 4.64 and 2.71 μ mole/mg protein/hr. respectively. The Mg^++ ATPase represented about 36.5% of the total ATPase in this group. 5. No significant changes of the Na^+K^+ ATPase and Mg^++ ATPase activities were found in the- group of cord trauma with administration of dexamethasone.
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