• The Korean Journal of Physiology
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• v.18 no.2
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• pp.163-169
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• 1984

The effect of vanadate on the optimum pH of Na-K-ATPase was investigated. The results were as follows: 1) The optimum PH of Na-K-ATPase was shifted from PH 7.4 to 6.8 at 10 mM K by $5{\times}10^{-6}M$ vanadate. 2) The ratio of Na-K-ATPase activity at pH 6.8 and 7.4 increased with increasing vanadate concentration. 3) Inspite of the presence of $5{\times}10^{-6}M$ vanadate Na-K-ATPase activity at pH 7.4 was higher than that at pH 6.8 below 50 mM $Na^+$, and the ratio of Na-K-ATPase activity at pH 7,4 and 6.8 was higher than that of the control. 4) Na-K-ATPase activity at pH 7.4 was higher than that at pH 6.8 below 7mM $K^+$. 5) Optimum pH of Na-K-ATPase activity was shifted from pH 7.4 to 6.8 by $10^{-5}M$ vanadate at 5 mM $K^+$. 6) $K^+$-pNPPase activity increased with lowering of pH, and the degree of inhibition of $K^+$-pNPPase activity by $10^{-7}$M vanadate was decreased with lowering of pH. These results suggest that vanadate shifts the optimum pH of Na-K-ATPase activity to more acidic PH than PH 7.4. This effect may not be caused by the decrease in the inhibitory potency of vanadate itself to Na-K-ATPase by the change of medium pH, but mainly by the alteration of Na-and K-binding site, which appears in the presence of vanadate only.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.9-11
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• 2002

Plasma membrane Na$^{＋}$-K$^{＋}$ ATPase (pump) is an essential component to maintain asymmetrical ion distribution across cell membrane. The Na$^{＋}$-K$^{＋}$ ATPase was discovered by Jens C. Skou in 1957 and since then physiological and biochemical properties of the enzyme have been extensively studied. Jens C. Skou was awarded the 1997 Nobel Prize in chemistry for his discovery of the Na $^{＋}$ - $K^{＋}$ ATPase.(omitted)

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.431-441
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• 1998

This study was undertaken to determine whether Buthus exract(BTE) affects Na^+-K^+-ATPase$ activity of nervous tissues. The enzym activity was measured in synaptosomal fraction prepared from rabbit brain cortex. Na^+-K^+-ATPase$ activity was inhibited by BTE over concentration range of 0.05-0.5% in a dose-dependent manner. The enzyme activity was increased by an increase in $Na^+$ concentration from 5 to 100mM, $K^+$ concentration from 0.5 to 10mM, and $Mg^{2+}$ concentration from 0.2 to 5mM. These changes in ion concentrations did not produce any effect on the inhibitory effect of BTE on $Na^+-K^+-ATPase$ activity. An increase in ATP concentration from 0.1 to 3mM caused an increase in the enzyme activity. The inhibition of the enzyme activity by BTE were not different between two ATP concentrations. A sulfhydryl group protector DTT prevented PCMB-induced inhibition of $Na^+-K^+-ATPase$ activity, but the BTE-induced inhibition was not altered by DTT. The inhibition of enzyme activity by combination of ouabain and BTE was not different from that by Buthus alone. These results suggest that Buthus exerts inhibitory effect on $Na^+-K^+-ATPase$ activity in cerebral synaptosomes, and the action mechansim is similar to that of ouabain.

• The Korean Journal of Pharmacology
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• v.19 no.1
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• pp.101-106
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• 1983

Vanadium is widely distributed in animal tissues and it is supposed to be a regulator of Na-K-ATPase activity. The effect of sodium orthovanadate on Na-K-ATPase activity in rabbit kidney was measured in vitro and compared with that of ouabain. The influence of sodium orthovanadate on the renal function of rabbits was also investigated. 1) Na-K-ATPase activity was decreased by sodium orthovandate at the concentrations of $10^{-7},\;10^{-6},\;10^{-5}\;and\;10^{-4}\;M$ to 73.89, 36.49, 6.50 and 4.99% of the control activity respectively. 2) Na-K-ATPase activity was decreased by ouabain at the concentrations of $10^{-4},\;10^{-3}\;and\;10^{-2}\;M$ to 69.52, 22.84 and 3.88% of the control activity respectively. 3) Urine volume, urinary excretion of $Na^+,\;K^+\;and\;Cl^-$, clearances of inulin and p-amino-hoppuric acid were decreased until after 60 minutes following the administration of sodium orthovanadate 0.5 mg/kg intravenously $Na^+\;reasorption$ rate was not changed and mean arterial pressure was significantly elevated during 60 minutes after the administration of sodium orthovanadate.

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.305-311
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• 1993

$Na^+,K^+$-ATPase activity, $Na^+$-dependent phosphorylation, and $[^3H]$ ouabain binding in sarcolemma prepared from 4 week old spontaneously hypertensive rat(SHR) ventricles were compared to the same parameters in sarcolemma from age matched nomotensive Wister-Kyoto (WKY) rat ventricles to examine whether the reduced myocardial $Na^+$-pump activity in SHR is an inherited enzymatic defect or a second phenomenon due to sustained hypertension. The total body weights, ventricular weights, and blood pressures were the same for SHR and WKY. No significant differences in sarcolemmal protein content and protein recovery were noted between the two groups. Sarcolemma isolated from SHR ventricles showed significantly less $Na^+,K^+$-ATPase activity ande number of phosphorylation sites when compared to sarcolemma from the WKY ventricles. Equilibrium binding of $[^3H]$ouabain and the tumover number of myocardial $Na^+,K^+$-ATPase, however, were the same for both groups. These reults indicate that the low affinity $(\alpha,\;or\;\alpha^1)\;\alpha$ isoform is the same in ventricles of SHR and WKY. The reduced amount of isoform of the $Na^+,K^+$-ATPase inprehypetensive SHR ventricles may play some role in the development of hypertension.

• The Korean Journal of Pharmacology
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• v.12 no.1
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• pp.7-14
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• 1976

Aconiti tuber butanol fraction shows positive inotropic effect on the isolated atrium of rabbit heart. To investigate the mechanism, the effect on microsomal ATPase activity of rabbit heart is observed. The microsomal fraction which contains the $Na^+$- and $K^+$-activated ATPase in the presence of $Mg^{++}$ is isolated from the left ventricle of rabbit heart. The microsomal ATPase activity is maximally stimulated at $Na^+$ and $K^+$ concentration of 100 mM and 10 mM respectively. Microsomal $Na^+-K^+$-activated ATPase is inhibited by ouabain and Aconiti tuber butanol fraction. Ouabain and Aconiti tuber butanol fraction depress $Na^+$-stimulation on microsomal ATPase activity, and the inhibitory effects are not completely reversed at $Na^+$ concentration of 300 mM. Also, $K^+$-stimulation on microsomal ATPase activity is inhibited by ouabin and Aconiti tuber butanol fraction and the inhibitions are not compeletely reversed at $K^+$ concentration of 30 mM. It is, therefore, suggested that the inhibitory effect of Aconiti tuber butanol fraction on the microsomal ATPase activity may contribute to leading to the positive inotropic effect.

• Toxicological Research
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• v.5 no.2
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• pp.79-87
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• 1989

Changes in urinary $Na^+$ and $K^+$ excretions, renal cortical microsomal $Na^+$ -K-ATPase activity, cortical tissue electrolyte content and plasma aldosterone level were studied in rats treated with CdCl2 (2 mg Cd/kg/day, s.c. injection) for 7-14 days. After 7 days of cadmium exposure, urinary excretion of $Na^+$ was markedly reduced. This change was accompanied by an increase in $Na^+$-$K^+$-ATPase activity, a fall in tissue $Na^+$ content, a rise in tissue $K^+$ content and an elevation of plasma aldosterone level.

• The Korean Journal of Physiology
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• v.9 no.1
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• pp.1-11
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• 1975

The present experiments were carried out to investigate the active center of sodium and potassium ion activated adenosine triphosphatase. An ATPase, activated by sodium ion Plus potassium ion in the presence of magnesium ion, and inhibited by ouabain, has been obtained from rabbit red cell ghosts. The ATPase activity was measured by inorganie phosphate released from ATP. From this values of the measured inorganic phosphate, the activity of ATPase was calculated. The following results were observed. 1. The activity of $(Na^++K^+)-ATPase$ is inhibited by ouabain. This effect may not be due to an effect on sulfhydryl groups, amino groups, carboxyl groups, imidazole groups and hydroxyl groups. 2. The $(Na^++K^+)$-activated enzyme system is inhibited by p-chloromercuribenzoate and by d nitroflurobenzene, and this effect may be due to an effect on sulfhydryl groups. These results indicate that the sulfhydryl groups is attached to sodium-potassium dependent adenosine triphosphate, an aspect of the pump. 3. The $(Na^++K^+)-activated$ enzyme system is inhibited by maleic anhydride and this inhibition is reversed by lysine. This Seems to indicate that the active center of this enzyme is the amino groups. 4. The $(Na^++K^+)$-activated enzyme system is inhibited by iodoacetamide and this inhibition is reversed by the simultaneous present of cysteine and aspartic acid in the suspension medium. This result indicates that this enzyme contains sulfhydryl groups and carboxyl groups. 5. The $(Na^++K^+)-ATPase$ activity is accelerated by adrenaline and this effect is abolished by aspartic acid. This effect of aspartic acid indicate that carboxyl group might be involved in the hydrolysis of ATP by the enzyme system. On the hydrolysis of ATP by the enzyme system. On the basis of these experiments it f·as suggested that the active center of $(Na^++K^+)-activated$ ATPase contains sulfhydryl groups, amino groups and carboxyl groups.

• Archives of Pharmacal Research
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• v.9 no.1
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• pp.29-38
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• 1986

The effects of ginseng saponins on the sarcolemmal $Na^{+}$, $K^{+}$-ATPase were compared to gypsophila saponin, sodium dodecylsulfate (SDS), and Triton X-100 to elucidate whether the effects are due to the membrane distruption, using a highly enriched preparation of cardiac sarcolemma prepared from dog ventricular myocardium. About 26% and 29% of vesicles in the preparation, enriched in ouabain-sensitive $Na^{+}$, $K^{+}$-ATP ase, $\beta$-adrenergic and muscarinic receptors are rightside-out and inside-out orientation, respectively. Ginseng saponins (triol>total> diol) inhibited $Na^{+}$, $K^{+}$-ATP ase activity, $Na^{+}$, $K^{+}$-ATPase activity and [$^{3}$H]ouabain binding of sarcolemmal vesicles. However, gypsophila saponin, SDS (0.4$\mu$g/$\mu$g protein) and Triton X-100 (0.6 $\mu$g/$\mu$g protein) caused about 1.35 and 1.40-fold increase in $Na^{+}$, $K^{+}$-ATPase activity and [$^{3}$H] oubain binding, respectively. Especially, the activating effect of gypsophila saponin on membrane Na+, K+ ATPase was detected at gypsophila saponin to sarcolemmal protein ratios as high as 100. Low dose of ginseng saponin (3$\mu$g/$\mu$g protein) decreased the phosphorylation sites and the concentration of ouabain binding sites (Bmax) without affecting the turnover number and affinity for ouabain binding, while gypsophila saponin, SDS(0.4 ug/ug protein), ahd Triton X-100 (0.6$\mu$g/$\mu$g protein) increased the Bmax. The results suggest that ginseng saponins cause a decrease in the number of active sites by interacting directly with $Na^{+}$, $K^{+}$-ATPase before disruption of membrane barriers of sarcolemmal vesicles.

• The Korean Journal of Physiology
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• v.17 no.2
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• pp.143-159
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• 1983

Vanadate가 가토 신피질절편에서 PAH이동과 Na-K-ATPase활성에 미치는 효과를 관찰한 결과 다음과 같은 결론을 얻었다. 1) Vanadate는 Na-K-ATPase활성을 농도에 따라 억제하였으며 $7.94{\times}10^{-7}M$에서 이 효소의 활성이 50% 억제되었다. 2) Vanadate는 PAH의 능동적이동을 농도에 따라 억제하였으며 50%억제농도는 대략 $10^{-4}M$ 이었고, 수동적이동에는 영향을 미치지 못하였다. 조직내 Na과 K의 양도 vanadate가 PAH이동을 억제하는 농도 범위에서 같이 변화하였고 산소소모량은 $10^{-4}M$까지는 약간 감소하였으나 $10^{-3}M$에서는 오히려 증가하였다. 3) 30분간 preincubation한 후에도 15분까지의 PAH이동은 30분 이후에 비해 vanadate에 의해 적게 억제되었다. 4) $10^{-4}M$ vanadate와 $10^{-4}M$ ouabain은 가역적으로 PAH 이동을 억제하였으며 $10^{-3}M$ vanadate는 비가역적으로 억제하였고 장시간 세척후에도 거의 같은 정도의 억제양상을 나타내었다. 5) Vanadate에 의한 PAH이동의 억제정도는 incubation용액내 $Na^+$의 감소, $K^+$의 증가에 의하여 증가하였고 $Ca^{2+}$의 농도 변화에 의해서는 영향을 받지 않았다. 6) Vanadate가 존재치 않을 때 Tris완충용액 사용시는 pH 8.2까지 PAH축적정도가 증가하였고 phosphate완충용액 사용시는 pH 7.4에서 최대축적치를 보였다. pH가 증가함에 따라 억제정도는 증가하였으며 같은 pH에서도 완충용액의 종류에 따라 vanadate에 의한 억제정도가 달랐다. 7) Vanadate와 ouabain은 PAH이등과 Na-K-ATPase활성에 부가적 억제작용을 나타내었다. 이상의 결과로 vanadate는 가토신장의 세포내부에서 Na-K-ATPase를 가역적으로 억제함으로써 PAH의 이동을 억제하는 것으로 생각되며 PAH의 이동은 Na-K-ATPase활성과 기능적으로 밀접히 연결되어 있는 것으로 생각된다.