• Biomedical Science Letters
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• v.4 no.1
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• pp.27-33
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• 1998

This study has been designed in order to examine a physiological role of $Ca^{2+}$ which has been known as an essential factor for capacitation, to confirm whether the enzyme activity of $Ca^{2+}$-ATPase on capacitation is important or not, and to clarify relationship between various levels of the $Ca^{2+}$ concentration and $Ca^{2+}$-ATPase which has been known to be an important factor of the plasma membranes. In the present study applying quercetin, a $Ca^{2+}$-ATPase inhibitor, the enzymatic effect of $Ca^{2+}$-ATPase on capacitation was found to be remarkable: a significant increase of the transition from the original type (type A) to the type B and the type AR of the spermatozoa. This finding suggests that $Ca^{2+}$-ATPase plays an important role in the efflux and the influx of the $Ca^{2+}$ which has been known to be an essential factor the capacitation and acrosome reaction, and that the inhibitory action of the $Ca^{2+}$-ATPase might be a prerequsite step toward the acrosome reaction. The conclusion reached can be deduced as follows: increment of the intracelluar $Ca^{2+}$ concentration occurred by controlling the slope of $Ca^{2+}$ concentration through $Ca^{2+}$-ATPase activities in both the intra- and extracelluar fluid may be an important procedure for capacitation and acrosome reaction, and ultimately for fertilization of the spermatozoa and the ova.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.5
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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.

• Development and Reproduction
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• v.15 no.1
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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.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.333-343
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• 1999

To investigate the relationship between the translocation and distribution the monovalent K and Na and the divalent Sr and Ca, the natrophile and calcitrophic plant sugar beet (Beta vulgaris L.) was used. Strontium uptake and distribution are concentration and growth stage dependent. The highest Ca content occurred in the treatment of 4 : 1 mM ratio of Ca to Sr, while the highest Sr content in old leaves in the presence of 1 mM Ca and 4 mM Sr. The addition of low concentration of Sr stimulates Ca-uptake. Reversely. Sr-uptake is highest in the presence of 1 mM Ca. This result may be an antagonistic effect between Ca and Sr. The ratios of Mg to Ca and Sr are satisfactorily presented by the regression analysis. The sum of Sr and Ca contents are most significant linear to the ratio of Mg to one, showing a negative correlation. This result implies that the absorption of Mg and Ca or Sr is antagonistic. In the presence of only 5 mM Sr, K and Na-uptakes increases, while Sr in the presence of Ca does not affect the change in the K and Na assimilation and their ratios. The ratios of K to Na is also not changed. A little addition of Sr could more effectively retain the chlorophyll loss while only in the presence of Sr, the chlorophyll levels are considerably reduced.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.3
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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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• v.12 no.2
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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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• 2006.08a
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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.

• The Korean Journal of Pharmacology
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• v.18 no.2
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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.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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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.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.253-259
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• 2008

Soil environmental conditions can affect nutrient availability during growth stage of tree fruit. We investigated the cause of disorderd fruit by the influence of soil chemical properties in orchard soil, composition of mineral nutrient in leaves and fruit to occur physiological disorderd fruit at four locations (Ulsan, Gyeongju, Pyeongtaek, Ansung) compared to healthy. There were significantly different (P=0.05) in exchangeable Ca, K, Mg and total nitrogen content in orchard soil between physiological disordered fruit and healthy fruit. The exchangeable Ca content in orchard soil caused by physiological disordered fruit was statistically lower than that of healthy fruit. However, exchangeable K, Mg and total nitrogen contents were higher than that healthy (P=0.05). There was a significant difference (P=0.05) in Ca content between physiological disordered fruit and healthy. Ca content in fruit flesh of physiological disorderedfruit was statistically lower than that of healthy. The physiological disordered fruit was a higher ratio of Mg/Ca in fruit flesh and peel compared to healthy fruit and also the ratios of N/Ca and K/Ca in a leaf were higher. The negative correlation between Ca and K, and Ca and Mg was detected in the fruit flesh of physiological disordered fruit. Therefore, we concluded that insufficient Ca content in fruit may cause 'the physiological disorder' pomelo disease and high content of N, exchangeable K and Mg ion in the soil solution might be disturbs exchangeable Ca ion to be absorbed in fruit.