• Korean Journal of Veterinary Research
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• v.29 no.3
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• pp.245-251
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• 1989

In order to manifest the presence of Na-K pump and its property on the unfertilized egg membranes of mouse, membrane potential was recorded under the physiological condition (at $37^{\circ}C$ and 4mM $Ca^{2+}$). After an induction of superovulation, the fresh eggs with zona pellucida were collected from mouse oviduct. Transient hyperpolarization as pump action was recorded after the switch into the high potassium perfusate (15mM $K^+$) from K-free perfusate, and the difference between membrane potential observed just before the perfusion of high potassium solution and the maximal membrane potenlial during the perfusion of high potassium solution was regard as pump activities. The results observed were as follows, 1. Resting mombrane potential was depolarized under the treatment of $10^{-5}M$ ouabain. 2. Pump activities of the unfertilized mouse eggs were $-3.38{\pm}0.61mV$ ($Mean{\pm}SD$, n=6), recorded as transient hyperpolarization due to the electrogenic property. 3. Pump activities were blocked by both treatment of $10^{-5}M$ ouabain and perfusion of Nafree solution, while increased by high $Na^+$ (300mM) perfusion ($-7.45{\pm}0.75mV$, n =2). 4. Hyperpolarization due to pump activity was not altered by $Mn^{2+}$. 5. Above results confirm the presence of ouabain-sensitive Na-K pump, which affected the membrane potential directly, on the unfertilized egg membranes of mouse.

• The Korean Journal of Physiology
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• v.27 no.2
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• pp.199-207
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• 1993

To study the underlying mechanism through which the endothelium-dependent relaxation is inhibited by blocking the $Na^+\;-K^+$ pump, the effects of $Na^+\;-K^+$ pump blockade on the release of EDRF and its relaxing activity were examined, using organ bath study, bioassay technique, and cGMP measurement. Endothelium-dependent relaxation was attenuated by blocking the $Na^+\;-K^+$ pump in the vascular ring with intact endothelium. In bioassay experiment EDRF release was decreased with the blockade of the $Na^+\;-K^+$ pump in the EDRF donor strip. Endothelium-dependent increase of cGMP level was suppressed by inhibiting the $Na^+\;-K^+$ pump in the test strips. The magnitude of relaxation of test strip which was induced by the perfusate that had passed through the EDRF donor strip was decreased with the blockade of the $Na^+\;-K^+$ pump in the test strip. Therefore, it could be suggested that the attenuation of endothelium-dependent relaxation caused by inhibiting $Na^+\;-K^+$ pump activity is due to both the decreased release of EDRF from endothelial cells and the decreased sensitivity of the smooth muscle cells to EDRF.

• Journal of Chest Surgery
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• v.28 no.12
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• pp.1079-1095
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• 1995

Recently endogenous digitalis-like substances were found in the blood of various cardiovascular diseases and they have been considered one of the causes of evoking hypertension. However, the mechanism of endogenous digitalis-like substances-induced hypertension is not clarified yet. Therefore, the effects of Na-K pump inhibition on the contractility of vascular smooth muscle[conduit and resistant artery were investigated, using organ bath and bioassay experiment. Aortic and carotid arterial rings[conduit artery and the branches of brachial and superior mesenteric artery[resistant artery were used to find the effect of Na-K pump inhibition. The results obtained were as followes;The magnitudes of contractions induced by norepinephrine, serotonin, or acetylcholine in all these arteries were significantly increased by the inhibition of Na-K pump. The increased contractile responses to these agonists, especially to serotonin, were much more prominant in resistant arteries. Nitroprusside-induced relaxations were attenuated by Na-K pump inhibition and there were no significant differences in the effects of Na-K pump inhibition on nitroprusside-induced relaxations of these blood vessels. Endothelium-dependent relaxation was suppressed by the inhibition of Na-K pump, especially by the administration of ouabain, and this inhibitory effect was much more prominent in the branches of superior mesenteric artery, compared with other arteries. In the branches of superior mesenteric arteries, endothelium-dependent relaxation was completely blocked by ouabain. The release of EDRF was partially suppressed by Na-K pump inhibition.From the above results, it is suggested that the hypertension due to the increase in vascular resistance can be evoked by the inhibition of Na-K pump and endogenous digitalis-like substances induce hypertension through this mechanism.

• The Korean Journal of Physiology
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• v.19 no.1
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• pp.15-23
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• 1985

Previous biochemical studies indicate that $(Na^++K^+)-ATPase$ is composed of two subunits, ${\alpha}$ and ${\beta}$, in a form of ${\alpha}_2{\beta}_2$ with a molecular weight of approximately 300,000 daltons. There is also suggestive evidence that the $Na^+$, $K^+$ pump in human erythrocytes occurs in a complex with some glycolytic enzymes. We assessed here in situ assembly size of the $(Na^++K^+)-ATPase$ of human erythrocytes by applying classical target theory to radiation inactivation data of the ouabain-sensitive sodium flux and ATP hydrolysis of intact cells and ghosts. Cells(in the presence of cryoprotective agent) and ghosts were irradiated at $-45^{\circ}C$ to $-50^{\circ}C$ with an increasing dose of a 1.5 MeV electron beam, and after thawing, the pump and/or enzyme activities were assayed. Each activity measured was decreased as a simple exponential function of radiation dose, from which a radiation sensitive volume (target size) was calculated. When intact cells were used, the target size of both $(Na^++K^+)-ATPase$ and $Na^+$, $K^+$ pump was found to be approximately 600,000 daltons. This target size of the ATPase was reduced to approximately 325,000 daltons if the cells were pretreated with strophanthidin. When ghosts were used, the target size of the ATPase was again approximately 325,000 daltons. Our target size measurement suggests that, in intact cells, the $(Na^++K^+)-ATPase/Na^+,K^+$ pump exists either as a dimer of $(\alpha\beta)_2$ which is a functional unit or as a monomer of $(\alpha\beta)_2$ but in tight complex with other enzyme or enzymes. The results also suggest that this dimeric or heterocomplex association is dissociated during ghost preparation and strophanthidin treatment.

• The Korean Journal of Physiology
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• v.16 no.1
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• pp.1-11
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• 1982

Force development of smooth muscle cells is directly regulated by the concentration of free calcium ions in the sarcoplasm, and the sarcoplasmic concentration of calcium ion can be modulated by electrogenic Na-K pump. The role of Na-K pump on vascular tone was studied in isolated rabbit renal artery. Helical strips of arterial muscle were prepared from left renal arteries. All experiments were performed in $HCO_3^--buffered$ Tyrode solution which was aerated with $3%CO_2-97%\;O_2$ mixed gas and kept at $35^{\circ}C$. In some experiments, rabbit was injected intraperitoneally $18{\sim}24$ hours prior to the experiments, with a large dose(5 mg/kg body wt) of reserpine, in order to eliminate the catecholamines present in intrinsic adrenergic nerve terminate. Treatment used in this experiment that inhibits Na-K pump was the exposure of strips to K-free Tyrode solution. Contractile response to K free Tyrode solution developed slowly and the time required for maximum contracture was $20{\sim}30$ minutes. This K-free contracture was rapidly relaxed by the addition of potassium to the bathing solution. No K-free contracture occurred in a Ca-free Tyrode solution. But contraction developed rapidly when calcium ion was added to the bathing solution after 30 minute exposure of the strip to Ca-free Tyrode solution. This contracture was completely inhibited by Ca-antagonist, verapamil. The K-free contracture was abolished by ${\alpha}-adrenergic$ blocker, phentolamine, as well as by the catecholamine depletion from adrenergic nerve terminals. Even in reserpinized strip, the exogenous norepinephrine-induced contraction in K-free Tyrode solution was rapidly suppressed by the addition of potassium ion. The results of this experiment suggest that K free contracture develops by norepinephrine release from adrenergic nerve terminals, while the relaxation of K-free contracture is induced by the activation of electrogenic Na-K pump.

• Korean Journal of Pharmacognosy
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• v.37 no.4 s.147
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• pp.272-277
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• 2006

This study was undertaken to determine whether Juglandis Semen (JAS) extract exerts protective effect against oxidant-induced inhibition of $Na^+-pump$ activity in cerebral cortex. $Na^+-pump$ activity was estimated by measuring ouabain-sensitive oxygen consumption. The oxygen consumption significantly inhibited by 1mM t-butylhydroperoxide (tBHP), which was prevented by addition of 2% JAS extract. The oxygen consumption was increased by an increase in $Na^+$ concentration from 5 to 100 mM, $K^+$ concentration from 0.5 to 10 mM, and $Mg^{2+}$ concentration from 0.2 to 5 mM. These changes in ion concentrations did not affect the inhibitory effect of tBHP and protective action of JAS on oxygen consumption. tBHP (l mM) produced a significant increase in lipid peroxidation in cerebral cortex, which was prevented by 2% JAS extraction. These results suggest that JAS exerts protective effect against tBHP-induced inhibition of $Na^+-pump$ activity in the cerebral cortex, probably through action as antioxidant.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.45-45
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• 2001

The Na$^{＋}$-K$^{＋}$ pump, a plasma membrane Na$^{＋}$-K$^{＋}$ ATPase is plays a key role in the regulation and maintenance of Na$^{＋}$ and $K^{＋}$ ion concentration gradients across cell membranes. This enzyme pumps three Na$^{＋}$ out of and two $K^{＋}$ into the cell against their electrochemical gradient by utilizing the energy derived from ATP. Therefore, the Na$^{+}$-K$^{+}$ pump generates a net outward electrical current.(omitted)ted)

• Journal of Pharmacopuncture
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• v.2 no.1 s.2
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• pp.13-25
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• 1999

This study was undertaken to determine whether Juglandis Semen (JAS) extraction exerts protective effect against oxidant-induced inhibition of $Na^+$-pump activity in cerebral cortex. $Na^+$-pump activity was estimated by measuring ouabain-sensitive oxygen consumption. The oxygen consumption significantly inhibited by 1 mM t-butylhydroperoxide (tBHP), which was prevented by addition of 2% JAS extraction. The oxygen consumption was increased by an increase in $Na^+$ concentration from 5 to 100mM, $K^+$ concentration from 0.5 to 10 mM, and $Mg^{++}$ concentration from 0.2 to 5 mM. These changes in ion concentrations did not affect the inhibitory effct of tBHP and protective action of JAS on oxygen consumption. tBHP(1mM) produced a significant increase in lipid peroxidation in cerebral cortex, which was prevented by 2% JAS extraction. These result suggest that JAS exerts protective effect against tBHP-induced inhibition of $Na^+$-pump activity in the cerebral cortex, this effect may be due to by an antioxidant action.

• The Korean Journal of Physiology
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• v.23 no.1
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• pp.35-42
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• 1989

The present study was performed to observe the effects of cations on resting membrane potential and pump activity in the unfertilized eggs of ICR strain mice. After an induction of superovulation, the fresh eggs with zona pellucida were collected and the membrane potentials were recorded. Recordings of membrane potential in this study was obtained from the physiological conditions ($37^{\circ}C$ and 4mM Ca in standard solution), differently from the another reports with unphysiological conditions (room temprature and high Ca in standard solution) for a stable and long-lasting observations. Presented data was obtained within 6 hours after collection from the oviduct. The results observed are as follows, 1) Resting potential of the unfertilized eggs was $-25.8{\pm}3.8mV$ $(Mean{\pm}Se,\;n=31)$. 2) As the K ion concentration was increased, resting membrane potential was depolarized but showed hyperpolarization with $K^{+}$ below 25mM. 3) Alteration of the resting membrane potential for the changes of $Na^{+}$ concentration were hardly observed, while resting potential was hyperpolarized as $Ca^{2+}$ concentration was increased. 4) Pump activity as transient or prolonged hyperpolarization was $-2.29{\pm}0.75mV$ $(Mean{\pm}Se,\;n=16)$, the hyperpolarization was increased in both amplitude and duration under the 10mM $Ca^{2+}$ solution. 5) Hyperpolarization due to pump activity was decreased or disappeared by $5{\times}10^{-5}\;M$ ouabain treatment and could not be observed under the both Na-free and Ca-free solutions. 6) Above results are likely to suggest that the resting potential of the mouse unfertilized eggs is affected to mainly by Ca-dependent K conductance and Na-Ca exchange mechanism and that there is pump activity coupling between $K{+}$, $Na^{+}$ and $Ca^{2+}$.

• The Korean Journal of Pharmacology
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• v.27 no.1
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• pp.33-43
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• 1991

To study the age dependent change of Na, K-ATPase in the erythrocyte of hypertensive rat, 1-kidey 1-clip hypertensive rat was made by the removal of right kidney and partial ligation of left renal artery. After 4 weeks, aged erythrocyte fraction was separated by density gradient centrifugation, and Na, K-ATPase activity and $^3H-ouabain$ binding with ghost cell membrane and ouabain sensitive Rb-uptake with whole cell were measured. 1) In the hypertensive rats, blood pressure was significantly increased to 165.5/119.0 mmHg (systolic/diastolic). Mean corpuscular volume and membrane protein(mg) per $10^9RBC$ were decreased and hemoglobin content was increased in the aged erythrocyte. 2) Na, K-ATPase activity in the solution containing 110 mM NaCl and 10 mM KCI, was decreased in hypertensive rat, and decreased in aged erythrocyte of both group. 3) Ouabain sensitive Rb-uptake by low RbCl concentration(4 mM) was slightly decreased in aged erythrocyte compared to that in young erythrocyte of each group, but slightly increased in young erythrocyte in hypertensive rat compared to that in normotensive rat. 4) Ouabain sensitive Rb-uptake by high RbCl concentration(16 mM) was decreased about 30% to 50 % in aged erythrocyte in both group. And in hypertensive rat, especially in young erythrocyte it was significantly decreased compared to that in normotensive rats. 5) $^3H-ouabain$ binding at 0.13 or $1{\times}10^-6M$ ouabain concentration was slightly decreased in aged erythrocyte of normotensive rat, and significantly decreased in aged erythrocyte of hypertensive rats. 6) $^3H-ouabain$ binding at 6 or $64{\times}10^-6M$ ouabain concentration is slightly decreased in aged erythrocyte of both group, but significantly decreased in young and aged erythrocyte of hypertensive rats compared to that of normotensive rats. The present results suggest that (1) in the young erythrocyte of hypertensive rat, the alterations of Na-pump activity that slightly increased in weak stimulation and inhibited in strong stimulation, may be related to increased molecular activity and the decrease in the number of low affinity site without change in high affinity site, (2) in the aged erythrocyte of normotensive rat, inhibited Na-pump may be related to the change in molecular activity of pump. (3) And in the aged erythrocyte of hypertensive rat, it may be related to the decrease in the number of high and low affinity site as well as the change in molecular activity