• 한국산학기술학회논문지
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• 제7권2호
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• pp.168-174
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• 2006

본 연구는 분자동력학 시뮬레이션을 이용하여 탄소 나노튜브를 이용한 전계효과 이온-전송 소자를 분석하였다. 외부 전기장에 의해 단전자 전계효과 트랜지스터 및 나노크기의 데이터 저장 장치로 활용될 수 있는 원리를 규명하였다. 외부 전기장이 증가할수록 칼륨 원자는 채널을 빠르게 통과하였다. 낮은 외부 전계에서는 나노채널의 열적 파동이 칼륨 원자의 터널링에 영향을 주게 됨을 해석하였다. 이로서 외부 전계의 강도에 따라 칼륨원자의 채널을 터널링하는 효과를 제어할 수 있는 메커니즘을 도출하였다.

• Journal of Korean Neurosurgical Society
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• 제38권5호
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• pp.375-379
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• 2005

Objective : Papaverine has been used in treating vasospasm following subarachnoid hemorrhage[SAH]. However, its action mechanism for cerebral vascular relaxation is not clear. Potassium channels are closely related to the contraction and relaxation of cerebral smooth muscle. Therefore, to identify the role of potassium and calcium channels in papaverine-induced vascular relaxation, we examine the effect of papaverine on potassium channels in freshly isolated smooth muscle cells from rat basilar artery. Methods : The isolation of rat basilar smooth muscle cells was performed by special techniques. The whole cell currents were recorded by whole cell patch clamp technique in freshly isolated smooth muscle cells from rat basilar artery. Papaverine was added to the bath solution. Results : Papaverine of $100{\mu}M$ into bath solution increased the amplitude of the outward $K^+$ current which was completely blocked by BKCa[large conductance calcium dependent potassium channels]blocker, IBX[iberiotoxin], and calcium chealator, BAPTA[l,2-bis[o-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid], in whole cell mode. Conclusion : These results strongly suggest that potassium channels may play roles in papaverine-induced vascular relaxation in rat basilar artery.

• Nutrition Research and Practice
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• 제14권1호
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• pp.55-61
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• 2020

BACKGROUND/OBJECTIVES: Osteoporosis is characterized by low bone mass and results in vulnerability to fracture. Calcium and vitamin D are known to play an important role in bone health. Recently, potassium has been identified as another important factor in skeletal health. We examined the link between potassium intake and bone health among the Korean older adult population. SUBJECTS/METHODS: This retrospective, cross-sectional study included 8,732 men and postmenopausal women over 50 years old who completed the Korean National Health and Nutrition Survey (KNHANES) between 2008 and 2011. Potassium consumption was evaluated using a 24-hour recall method. Bone mineral density (BMD) was measured at three sites (total hip, femur neck, and lumbar spine) by dual-energy X-ray absorptiometry (DEXA). Multinomial logistic regression was used to examine the link between potassium intake and prevalence of osteoporosis and osteopenia, after controlling for potential confounding variables. RESULTS: The BMD of the total femur and Ward's triangle were significantly different according to the potassium intake among men (P = 0.031 and P = 0.010, respectively). Women in the top tertile for potassium intake showed higher BMD than those in the bottom tertile at all measurement sites (all P < 0.05). Daily potassium intake was significantly related to a decreased risk of osteoporosis at the lumbar spine in postmenopausal women (odds ratios: 0.68, 95% confidence interval: 0.48-0.96, P trend = 0.031). However, the dietary potassium level was not related to the risk of osteoporosis in men. CONCLUSION: Current findings indicate that higher dietary potassium levels have a favorable effect on bone health and preventing osteoporosis in older Korean women.

• The Korean Journal of Physiology and Pharmacology
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• 제17권6호
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• pp.537-546
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• 2013

Deiters' cells are the supporting cells in organ of Corti and are suggested to play an important role in biochemical and mechanical modulation of outer hair cells. We successfully isolated functionally different $K^+$ currents from Deiters' cells of guinea pig using whole cell patch clamp technique. With high $K^+$ pipette solution, depolarizing step pulses activated strongly outward rectifying currents which were dose-dependently blocked by clofilium, a class III anti-arrhythmic $K^+$ channel blocker. The remaining outward current was transient in time course whereas the clofilium-sensitive outward current showed slow inactivation and delayed rectification. Addition of 5 mM tetraethylammonium (TEA) further blocked the remaining current leaving a very fast inactivating transient outward current. Therefore, at least three different types of $K^+$ current were identified in Deiters' cells, such as fast activating and fast inactivating current, fast activating slow inactivating current, and very fast inactivating transient outward current. Physiological role of them needs to be established.

• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.1-15
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• 1990

The aim of this study was to investigate the effect of dental therapeutic agent on conduction velocity and threshold current of intradental A- and C-fibers in the cat. Inferior alveolar nerve of cat anesthetized with sodium pentobarbital was exposed and dissected until response of functional single pulp nerve until could be evoked by monopolar electrical stimulation of the crown of the lower left canine teeth. 10ms rectangular pulse was used to determine the threshold current and 1ms rectangular pulse was used to determine conduction velocity. After application of calcium chloride (1, 2, 6M), calcium hydroxide mixed with saline, potassium chloride (0.2, 0.8, 1.6M), eugenol, zinc oxide eugenol to the cavity on the labial surface, conduction velocity and threshold current of single pulp nerve unit were compared with the control. In 10 cats, 24 $A{\delta}$- and 11 C- pulp nerve units were recorded. The mean conduction velocities of $A{\delta}$- and C-fibers were 7.5m/sec (SD=5.8) and 1.2m/sec (SD=0.4), respectively. The mean threshold current was $12.3{\mu}A$ (SD=5.3) for $A{\delta}$-fibers and $24.9{\mu}A$ (SD=8.1) for C-fibers. 1, 2, 6M calcium chloride caused decrease of conduction velocity and remarkable increase of threshold current in $A{\delta}$- and C-fibers. The effect of calcium hydroxide mixed with saline was similar but smaller than calcium chloride solution. 0.2M potassium chloride had insignificant effect. In 0.8M potassium chloride, the threshold current was increased although conduction velocity was not affected. In 1.6M potassium chloride, the threshold current was increased and the conduction velocity was slowed down. Spontaneous activity was recorded frequently for first 5 min but gradually reduced both in $A{\delta}$- and C-fibers. Eugenol had irreversible effect on pulp nerve in that initially there were not certain changes in the conduction velocity and threshold current of $A{\delta}$- and C-fibers, but the responses to electrical stimulation were abruptly disappeared after sustained application and were not recovered. Contrary to eugenol, zinc oxide eugenol did not caused significant increase of the threhold current and caused time dependent decrease of the conduction velocity, and did not show any irreversible change.

• Restorative Dentistry and Endodontics
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• 제18권2호
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• pp.469-481
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• 1993

The purpose of this study was to achieve the reduction of the galvanic current between the dental amalgam alloy and gold alloy. In order to measure the galvanic current between these two metals a prep in the size of $4{\times}13mm$ which was filled with amalgam and another prep of $4{\times}2mm$ was filled with gold alloy was made in the acrylic resin. These two preps were then connected to a 2mm diameter copper wire. Using an ammeter to measure the galvanic current, six different kinds of amalgam and gold alloy were immersed in saline solution with approximately 10mm distance between the two alloys. Chemical agents that are thought to reduce the galvanic current such as hydrazine. silver nitrate, potassium chromate, and bonding agents such as Scotch bond 2(3M) and All bond 2(Bisco) were applied to the alloy surface. Cathodic inhibitor such as hydrazine was applied to gold alloy where as anodic inhibitor such as silver nitrate and potassium chromate were applied to amalgam. Both bonding agents, Scotch bond 2(3M) and All bond 2 (Bisco), were applied to amalgam. The following results were obtained when the currency on the coated alloy surface was compared to the uncoated surface. 1. The galvanic currency went down as the time elapsed and after 30 minutes no change was detected. 2. Initial currency was higher in low copper amalgam compared to high copper amalgam. Intitial currency was the highest in low copper lathe-cut amalgam. 3. Group of gold coated with hydrazine had the most reduction in galvanic currency. 4. Group of amalgam coated with silver nitrate or potassium chromate also showed significant reduction in galvanic currency. 5. The bonding agents also helped reduce galvanic currency. 6. Of all the agents used to reduce galvanic currency, silver nitrate showed the best result.

• 수산해양교육연구
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• 제10권1호
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• pp.79-86
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• 1998

In this study, the adhesive effect, blistering behavior and electrochemical polarization behavior of red lead film by the pretreatment work of sandblasting and potassium chromate($K_2CrO_4$) were investigated to prevent the corrosion of gas storage tank under marine environment. The main results obtained are as follows : 1) The adhesive effect of red lead film by the pretreatment work of sandblasting and potassium chromate is more improved than that of red lead film. 2) The blistering occurrence of red lead film by the pretreatment work of sandblasting and potassium chromate is more delayed than that of red lead film. 3) As the anodic potential is increased, corrosion current density of red lead film by the pre treatment work of sandblasting and potassium chromate is lower drained than that of red lead film.

• The Korean Journal of Physiology
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• 제26권1호
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• pp.27-35
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• 1992

We used the whole cell patch clamp technique to examine the ionic basis for the tail current after depolarizing pulse in single atrial myocytes of the rabbit. We recorded the tail currents during various repolarizations after short depolarizing pulse from a holding potential of -70 mV. The potassium currents were blocked by external 4-aminopyridine and replacement of internal potassium with cesium. The current was reversed to the outward direction above +10 mV. High concentrations of intracellular calcium buffer inhibited the activation of the current. Diltiazem and ryanodine blocked it too. These data suggest that the current is activated by intracellular calcium released from sarcoplasmic reticulumn. When the internal chloride concentration was increased, the inward tail current was increased. The current was partially blocked by the anion transport blocker niflumic acid. The current voltage curve of the niflumic acid sensitive current component shows outward rectification and is well fitted to the current voltage curve of the theoretically predicted chloride current calculated from the constant field equation. The currents recorded in rabbit atrial myocytes, with the method showing isolated outward Na Ca exchange current in ventricular cells of the guinea pig, suggested that chloride conductance could be activated with the activation of Na/ca exchange current. From the above results it is concluded that a chloride sensitive component which is activated by intracellular calcium contributes to tail currents in rabbit atrial cells.

• The Korean Journal of Physiology and Pharmacology
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• 제1권3호
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• pp.233-240
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• 1997

Neurons in the nucleus raphe magnus are involved in descending modulation of nociceptive transmission. In this study, we attempted to investigate electrophysiological properties of the NRM neurons dissociated from the postnatal rat medulla. The NRM neurons in the coronal slices of and the dissociated neurons from the postnatal rat medullae were immunohistochemically identified using antibody against serotonin. Relatively small number of neurons were positively stained in both preparations. The positively stained neurons displayed large cell body with double or multiple neurites. Using whole-cell patch clamp configuration ionic currents were recorded from the dissociated NRM-like neurons selected by criteria such as size and shape of cell body and cell population. Two types, high- and low-threshold, of voltage-dependent calcium currents were recorded from the dissociated NRM-like neurons. Some neurons displayed both types of calcium currents, whereas others displayed only high-threshold calcium current. Voltage-dependent potassium currents were also recorded from the dissociated NRM neurons. Some neurons displayed both transient outward and delayed rectifier currents but others showed only delayed rectifier current. These results suggest that there are at least two types of calcium currents and two types of potassium currents in the dissociated NRM neurons.

• 대한조선학회지
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• 제7권1호
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• pp.45-56
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• 1970

The penetration of domestic high-titania potassium type arc welding rod has been investigated experimentally. The penetration of this type arc welding rod is influenced much more by changing welding current than welding speed and thickness of base metal in range of $6{\sim}9mm$. Values of penetrations were $1.00{\sim}1.75mm$ for $3.2mm{\phi}$ rod, and $1.10{\sim}1.86mm$ for $4mm{\phi}$ rod in adequate welding current range. The domestic rod's penetration is deeper than same type rod of the United State's product.