• 대한의생명과학회지
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• 제4권1호
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• pp.27-33
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• 1998

세포내, 외 $Ca^{2+}$ 농도구배 유지에는 $Ca^{2+}$-ATPase와 $Ca^{2+}$-$Na^{+}$ exachangers가 주요한 기능을 한다고 알려져 있는데 특히 $Ca^{2+}$-ATPase의 기능에 대해 많은 연구가 행해지고 있다 $Ca^{2+}$-ATPase는 체세포에서 세포막에 위치하고 있으며 $Ca^{2+}$을 세포외부로 배출하는 기능을 함으로써 세포내부의 $Ca^{2+}$농도를 낮게 유지할 수 있도록 하는 기능을 담당하고 있다. 이러한 $Ca^{2+}$-ATPase는 포유동물의 정자에도 존재하고 있지만 그 기능에 대해서는 아직 많은 설명이 되어있지 않다. 본 연구에서 정자가 수정을 하기 위한 기능적인 능력이 $Ca^{2+}$ 농도와 관련된 변화와 얼마나 연관되어 있는가를 규명하고, 이러한 $Ca^{2+}$ 농도 조절이 원형질막의 중요인자인 $Ca^{2+}$-ATPase와는 어떠한 연관성이 있는가를 알기 위해 시도한 결과, $Ca^{2+}$-ATPase는 세포내, 외 $Ca^{2+}$의 농도구배를 조절함으로써 세포내 $Ca^{2+}$의 농도를 증가시켜 정자가 수정능 획득과정으로 빨리 전환하도록 유도하고 첨체 반응에 중요한 역할을 하는 것으로 판단되며, 세포외 $Ca^{2+}$ 농도가 높게 유지될 경우에도 정자의 첨체반응이 유도됨으로써 난자와 용이하게 수정을 할 수 있는 생리적 환경이 제공될 수 있다고 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권5호
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• pp.611-616
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• 1998

Although the $Ca^{2+}-activated\;K^+\;(I_{K,Ca})$ channel is known to play an important role in the maintenance of resting membrane potential, the regulation of the channel in physiological condition is not completely understood in vascular myocytes. In this study, we investigated the role of cytoplasmic $Mg^{2+}$ on the regulation of $I_{K,Ca}$ channel in pulmonary arterial myocytes of the rabbit using the inside-out patch clamp technique. $Mg^{2+}$ increased open probability (Po), but decreased the magnitude of single channel current. $Mg^{2+}-induced$ block of unitary current showed strong voltage dependence but increase of Po by $Mg^{2+}$ was not dependent on the membrane potential. The apparent effect of $Mg^{2+}$ might, thus, depend on the proportion between opposite effects on the Po and on the conductance of $I_{K,Ca}$ channel. In low concentration of cytoplasmic $Ca^{2+},\;Mg^{2+}$ increased $I_{K,Ca}$ by mainly enhancement of Po. However, at very high concentration of cytoplasmic $Ca^{2+},$ such as pCa 5.5, $Mg^{2+}$ decreased $I_{K,Ca}$ through the inhibition of unitary current. Moreover, $Mg^{2+}$ could activate the channel even in the absence of $Ca^{2+}.\;Mg^{2+}$ might, therefore, partly contribute to the opening of $I_{K,Ca}$ channel in resting membrane potential. This phenomenon might explain why $I_{K,Ca}$ contributes to the resting membrane potential where membrane potential and concentration of free $Ca^{2+}$ are very low.

• 한국토양비료학회지
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• 제32권4호
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• pp.333-343
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• 1999

본 연구는 호염성(胡鹽性) 이면서 호칼슘 식물로 알려진 사탕무에서 일가이온인 K와 Na 그리고 이가 이온인 Ca와 Sr 및 Mg의 식물체내 수송과 분포를 밝히고자 수행하였다. Sr의 흡수와 재분배과정은 근권의 이온농도와 생육단계와 밀접한 관계가 있었다. Ca 4 mM과 Sr 1 mM을 처리했을 때 체내 Ca 함량이 가장 높았던 반면 Sr의 함량은 1mM Ca와 4 mM Sr을 혼합처리 했을 때 가장높았다. 즉 낮은 농도의 Sr을 처리했을 때 Ca의 흡수가 가장 높았다. 이러한 결과는 Ca와 Sr의 상가적 흡수기작 때문으로 추정되었다. Mg함량에 대한 Ca와 Sr총 함량은 고도의 부의 상관을 나타냈다. 결과적으로 Mg와 Sr 및 Ca는 상호 길항적으로 흡수되는 것을 알수 있었다. 5mM Sr 존재 하에서만 K와 Na의 흡수가 증가하는 반면 Ca와 Sr의 혼합처리는 이들 이온과는 무관하였다. 따라서 K/Na Ratio 또한 변화되지 않았다. 소량(1mM)의 Sr 첨가는 Chlorophyll 분해를 저지하는 효과를 보였다.

• 한국발생생물학회지:발생과생식
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• 제15권1호
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• pp.31-39
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• 2011

Change in intracellular $Ca^{2+}$-concentration ($[Ca^{2+}]_i$) is an essential event for egg activation and further development. $Ca^{2+}$ ion is originated from intracellular $Ca^{2+}$-store via inositol 1,4,5-triphosphate receptor and/or $Ca^{2+}$ influx via $Ca^{2+}$ channel. This study was performed to investigate whether changes in $Ca^{2+}$/calmodulin dependent protein kinase II (CaM KII) activity affect $Ca^{2+}$ influx during artificial egg activation with ethanol using $Ca^{2+}$ monitoring system and whole-cell patch clamp technique. Under $Ca^{2+}$ ion-omitted condition, $Ca^{2+}$-oscillation was stopped within 30 min post microinjection of porcine sperm factor, and ethanol-induced $Ca^{2+}$ increase was reduced. To investigate the role of CaM KII known as an integrator of $Ca^{2+}$- oscillation during mammalian egg fertilization, CaM KII activity was tested with a specific inhibitor KN-93. In the eggs treated with KN-93, ethanol failed to induce egg activation. In addition, KN-93 inhibited inward $Ca^{2+}$ current ($I_{Ca}$) in a time-dependent manner in whole-cell configuration. Immunostaining data showed that the voltage-dependent $Ca^{2+}$ channels were distributed along the plasma membrane of mouse egg and 2-cell embryo. From these results, we suggest that $Ca^{2+}$ influx during fertilization might be controlled by CaM KII activity.

• 열처리공학회지
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• 제26권3호
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• pp.113-119
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• 2013

Grain growth behaviors of hot-rolled AZ31 (Mg-3%Al-1%Zn) and AZ31-0.3%CaO alloys at elevated temperatures have been investigated in order to clarify the effect of CaO addition on grain stability of Mg-Al-based wrought alloy. The grain size of CaO-free alloy increased steeply from 673 K with an increase in annealing temperature from 573 to 773 K, whereas the grains of CaO-containing alloy were relatively stable up to 723 K. The activation energies for grain growth ($E_g$) were 12.2 and 18.3 kJ/mole between 573 and 673 K and 119.2 and 126.9 kJ/mole between 673 and 773 K in the AZ31 and AZ31-0.3%CaO alloys, respectively. This result indicates that grains in the CaO-added alloy possess higher thermal stability than CaO-free alloy. SEM observations on the annealed alloy samples revealed that higher grain stability resulting from CaO addition would be associated with the suppression of grain growth by Ca-related precipitate particles distributed in the microstructure.

• Archives of Pharmacal Research
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• 제12권2호
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• pp.128-134
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• 1989

$Na^+-Ca^{2+}$ exchange process in sarcolemmal vesicles isolated from mesenteric arteries of Wistar-Kyoto normotensive(WKY) and spontaneously hypertensive rats(SHR) was investigated. The sarcolemmal fractions isolated after homogenization and sucrose density gradient centrifugation were enriched with 5'-nucleotidase and ouabain sensitive, $K^+-dependent$ phosphatase activities. When the vesicles were loaded with $Na^+$, a time dependent $Ca^{2+}$ uptake was observed. However, very little $Ca^{2+}$ uptake was observed when the vesicles were loaded with $K^+$, or $Ca^{2+}$ uptake of the $Na^+-loaded$ vesicles was carried out in high sodium medium so that there was no sodium gradient. When the vesicles loaded with $Ca^{2+}$ by $Na^+-Ca^{2+}$ exchange were diluted into potassium medium containing EGTA, $Ca^{2+}$ was rapidly released from the vesicles. $Na^+-dependent\;Ca^{2+}$ uptake was increased in SHR compared to WKY, but passive efflux of preaccumulated $Ca^{2+}$ from the vesicles was decreased in SHR. The data indicate that the membrane vesicles of rat mesenteric arteries exhibit $Na^+-Ca^{2+}$ exchange activity. It is also suggested that changes of this process in vascular smooth muscle cell membrane of SHR may be involved in higher intracellular $Ca^{2+}$ concentration and higher basal tone in SHR.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1071-1074
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• 2006

Ca/Ag double layer which is fabricated by thermal evaporation exists as the double layer of (Ca+O)/(Ag+Ca). In Ca layer, are crystalline Ca(OH)2 and amorphous Ca and in Ag layer, are crystalline Ag and amorphous Ca. And for the certain thickness of Ag, in the Ca/Ag double layer, the thicker Ca is, the higher transmittance is.

• 대한약리학회지
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• 제18권2호
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• pp.89-102
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• 1982

The $Na^+-and\;K^+-induced\;Ca^{++}$ release was measured isotopically by millipore filter technique in pig heart mitochondria. With EGTA-quenching technique, the characteristics of mitochondrial $Ca^{++}-pool$ and the sources of $Ca^{++}$ released from mitochondria by $Na^+\;or\;K^+$ were analyzed. The mitochondrial $Ca^{++}-pool$ could be distinctly divided into two components: internal and external ones which were represented either by uptake through inner membrane, or by energy independent passive binding to external surface of mitochondria, respectively. In energized mitochondria, a large portion of $Ca^{++}$was transported into internal pool with little external binding, while in de-enerigzed state, a large portion of transported $Ca^{++}$ existed in the external pool with limited amount of $Ca^{++}$ in the internal pool which was possibly transported through the $Ca^{++}-carrier$ present in the inner membrane. $Na^+$ induced the $Ca^{++}$ release from both internal pool and external pool and external binding pool of mitochondria. In contrast, $K^+$ did not affect $Ca^{++}$ of the internal pool, but, displaced $Ca^{++}$ bound to external surface of the mitochondria. When the $Ca^{++}-reuptake$ was blocked by EGTA, the $Ca^{++}$ release from the internal pool by $Na^+$ was rapid; the rate of $Ca^{++}-efflux$ appeared to be a function of $[Na^+]^2$ and about 8mM $Na^+$ was required to elicit half-maximal velocity of $Ca^{++}-efflux$. So it was revealed that $Ca^{++}-efflux$ velocity was particulary sensitive to small changes of the $Na^+$ concentration in physiological range. Energy independent $Ca^{++}-binding$ sites of mitochondrial external surface showed unique characteristics. The total number of external $Ca^{++}-binding$ sites of pig heart mitochondria was 29 nmoles per mg protein and the dissociation constant(Kd) was $34{\mu}M$. The $Ca^{++}-binding$ to the external sites seemed to be competitively inhibited by $Na^+\;and\;K^+$; the inhibition constant(Ki) were 9.7 mM and 7.1 mM respectively. Considering the intracellular ion concentrations and large proportion of $Ca^{++}$ uptake in energized mitochondria, the external $Ca^{++}-binding$ pool of the mitochondria did not seem to play a significant role on the regulation of intracellular free $Ca^{++}$ concentration. From this experiment, it was suggested that a small change of intracellular free $Na^+$ concentration might play a role on regulation of free $Ca^{++}$ concentration in cardiac cell by influencing $Ca^{++}-efflux$ from the internal pool of mitochondria.

• 열처리공학회지
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• 제17권3호
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• pp.173-179
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• 2004

In this study, the influence of heat treatment and Ca contents on the electrochemical behavior was investigated. Mg-Ca alloys, i.e., Mg-0.22wt%Ca, Mg-0.56wt%Ca, Mg-1.31wt%Ca are prepared by ingot metallurgy. As-cast Mg-Ca alloys exhibited better electrochemical properties than pure Mg. Especially, Mg-0.22wt%Ca alloy improves its anode efficiency up to 62% and lowers the OCP up to -1.72VSCE. Microstructure and XRD patterns of Mg-Ca alloys show that additive Ca element is mainly solid-solutioned. While, the others show the microstructure and XRD pattern with large $Mg_2Ca$ at grain boundary. To assess the effect of heat treatment on the as-cast Mg-alloy, the specimens were heat treated at $200^{\circ}C$ for 2 hours under $CO_2$ gas atmosphere. Although corrosion properties of Mg-Ca alloys are somewhat deteriorated by heat treatment at $200^{\circ}C$ Mg-0.22wt%Ca alloy with uniformly distributed nano-sized $Mg_2Ca$ phase in ${\alpha}$-Mg matrix show still better corrosion properties than pure Mg specimen.

• 한국환경농학회지
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• 제27권3호
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• pp.253-259
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• 2008

과수의 생육기간동안 양분흡수는 과원토양의 환경에 영향을 받는다. 수확기에 신고 배에 Ca 결핍장해과로 보이는 과실의 발생 원인을 조사하기 위하여 과실에 생리장해가 발생한 4개 지역(울산,경주,평택,안성)의 과원 토양의 화학성 및 잎과 과실의 무기성분 함량을 조사하였다. 과실에 생리장해가 발생한 과원 토양의 치환성 Ca 함량은 정상관원에 비해 낮은 반면, 치환성K와 Mg 함량 및 T-N 함량은 높았다(P=0.05). 생리장해 과실의 과육과 과피의 Ca 함량은 건전한 과실에 비해 낮았으며, 과육과 과피의 Mg/Ca 비율은 건전 과실보다 높았다(P=0.05). 잎에 N/Ca 및 K/Ca 비율은 생리장해가 발생한 나무가 건전한 나무의 잎 보다 높았다. 따라서 신고 배의 생리장해는 Ca 함량의 부족에 의해 발생하는 유부과로 판단되며, 이는 토양에 치환성 K와 Mg 이온 및 T-N가 Ca 이온의 흡수에 장해요인으로 작용한 것으로 생각된다.