• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.364-369
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• 1992

This study was carried out to investigate the effect of rootzone temperature on uptake and translocation of Ca-45 in melon(Cucumis meol L. var ; Sineunchun and Keumssaragi) treated radioisotope(Ca-45) for 24 hours in hydroponics which controlled the nutrient solution temperature as $15^{\circ}C$, $22^{\circ}C$, and $32^{\circ}C$. In two varieties of melon, content and translocation of Ca-45 were high in the stems as compared with the leaves and the fruits and continued to increase with increase in temperature of the hydroponics. Content and translocation of Ca-45 in the leaves and the fruits of Sineunchun variety continued to increase with increase in the temperature, but there was rather decrease in Keumssaragi variety at $32^{\circ}C$. Most Ca-45 absorbed was translocated to the shout apices, and great amount was determined in the fruits as compared with the leaves.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.2
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• pp.80-85
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• 2006

The foliar injuries and absorption rates of calcium compounds in tomato (Lycopersicon esculentum cv. momotaro) and citrus [Shiranuhi(C. Marc. ${\time}C$. sinensis Osbeck)${\time}C$. reticulata Blanco)] were investigated. 0.3, 0.5 and 1.0% of $CaCl_2$, $Ca(NO_3)_2$, $Ca(H_2PO_4)_2$, Ca-EDTA, Ca formate or Ca acetate solution were applied to the leaves of tomato and citrus. The leaf burns were observed only in the foliar applications of Ca-EDTA and $Ca(H_2PO_4)_2$. Ca-EDTA exhibited more serious foliar injury than CaH2PO4. As applied with $^{45}CaCl_2$, $^{45}Ca(NO_3)_2$, $^{45}Ca$ formate or $^{45}Ca$ acetate, the rates of Ca absorptions by tomato and citrus leaves for 7 days were 17 to 32% and 6.6 to 46%, respectively. It meant that the absorption was differently influenced on calcium compounds. In tomato, the order of Ca foliar absorption was $Ca(NO_3)_2$ > Ca formate = $CaCl_2$ > Ca acetate. Although there was no difference in Ca absorption between the adaxial and abaxial parts of tomato leaves, total absorption was greater in expanded leaves than in expanding ones. On the other hand, in citrus Ca foliar absorption from $Ca(NO_3)_2$ or Ca formate was more active than that from $CaCl_2$ or Ca acetate. In conclusion, $Ca(NO_3)_2$ and Ca formate are recommended for the foliar application of Ca in tomato and citrus in order to increase absorption of Ca into their leaves.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.153-159
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• 1987

Adsorption and desorption characteristics of $^{42}K$ and $^{45}Ca$ were studied by making use of the natural zeolite, bentonite, and vermiculite. The work included that the fittness tests for the Freundlich and the Langmuir adsorption isotherms and desorption of the radionuclides from adsorbents by extracting with $NH^+_4$ ($1N-NH_4OAc$). The adsorption by the radionuclides are fitted well with both of the adsorption equations. The Langmuir adsorption maximum of $^{42}K$ is higher than that of $^{45}Ca$ by the zeolite and bentonite except vermiculite, and the values of $^{42}K$ decrease in the order of Zeolite (Zt)>Bentonite (Bt)>Vemiculite (Vt). As for $^{45}Ca$, the maximum adsorption values decrease in the order of Bt>Vt>Zt. The ionic radii of K and Ca seem to be closely related with fixation in the cavity of the zeolite that adsorb more $^{42}K$ than $^{45}Ca$. The smaller ionic size of Ca seems to be resulted in the lower adsorption of $^{45}Ca$ by the zeolite because Ca could leave easily from the cavity. Ionic size of K, however, seems to be similar with size of the cavity. $^{45}Ca$ adsorption by the bentonite, on the other hand, show higher adsorption than $^{42}K$. The higher charge density of the divalent cations than those of the monovalent cations seems to be the main consideration. For the retention strength of the adsorbed $^{42}K$ and $^{45}Ca$ by the adsorbents, a comparison is made by use of the Langmuir constant(k). The results indicated that the constant values for K are smaller than those of Ca in all the adsorbents. It seems that the smaller values of the constant, the weaker retention strength. For $^{42}K$, the percentage of desorption decrease in the order of Zt>Bt>Vt, but in the case of $^{45}Ca$, it decreases in the order of Vt>Zt>Bt. The results show that the weaker binding strength as represented by small value of the Langmuir constant, the higher percentage of the removal except fixing preferably $K^+$ by the vemiculite. In conclusion, the zeolite could adsorb much more $^{42}K$ and remove it more than others. For $^{45}Ca$, the bentonite could adsorb more and desorb less than others.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.80-87
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• 1987

To get a better insight into the exxistence and the role of a Na-Ca exchange mechanism in smooth muscle, the effect of Na substitution with sucrose on tension development, cellular Ca uptake and $^{45}Ca$ efflux was investigated using isolated cat ileal longitudinal muscle strips. Experimental results were summarized as follows;1) Exposure of the cat ileal longitudinal muscle to Na-free solution induced a contraction, and the magnitude of the contraction increased after incubation of the muscle strips with ouabain ($2{\times10^{-}5}$M) for 1hr. 2) Cellular Ca uptake in Na-free solution increased with an increase in Na content of the Na-loading media, and a linear relationship existed between tissue Na content and cellular Ca uptake for 10 min 3) After tissues were equilibrated in PSS containing $^{45}Ca$ for 2hr, cellular Ca uptake decreased with rising the external Na concentration. 4)Removal of medium Na or inhibition of the Na-K pump decreased the rate of $^{45}Ca$ efflux. These results strongly suggested that Na substitution increases cellular Ca uptake and decreases the rate of $^{45}Ca$ efflux via a Na-Ca exchange mechanism.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.1
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• pp.41-45
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• 1983

The method of intestinal Ca absorption in rats was studied by injecting the test solution of $^{45}Ca$ into ligated ileal loops (an in situ closed gut sement technique). The amount of Ca absorbed was measured in regard to the amount of soluble $^{40}Ca$ and $^{45}Ca$ which disappeared from the ligated ileal loops for 30min, and appeared portal blood for 15 min after the injection. The 15~20cm ligated segment of mid ileum and the test solution containing $0.2{\sim}0.5{\mu}Ci$ $5{\mu}g$ Ca/0.5ml, pH 7.0, $37^{\circ}C$ are appropriate for this in situ closed gut segment technique which turn out to be highly available for study of Ca absorption. The rats fed casein diet absorbed more Ca by 2~5 times than the rats fed egg albumin diet.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.189-194
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• 1996

The effects of scorpion (Leiurus quinquestriatus hebraeus, Lqh) venom were evaluated on the activities of microsomal $Ca^{2+}-ATPase$ and $Ca^{2+}$ release channel prepared from the epithelial cells of pig airway. Whole venom of Lqh $(120\;{\mu}g/ml)$ increased the activity of microsomal $Ca^{2+}-ATPase$ about 32% in the tight-sealed microsomes and about 28% in the Triton X-100-treated or $Ca^{2+}$ ionophore A23187-treated leaky microsomes. Thapsigargin, a specific antagonist of $Ca^{2+}-ATPase$, inhibited 42% of total ATPase activity and also completely blocked the effects of Lqh venom, suggesting that Lqh venom directly activiates the microsomal $Ca^{2+}-ATPase$. In order to determine if Lqh venom increases the microsomal uptake of $^{45}Ca^{2+}$, Lqh venom was added in the uptake medium. The Lqh venom increased microsomal $^{45}Ca^{2+}$ uptake up to ${\sim}20%$ and the increase was only observed when heparin, an antagonist of $InsP_3$ receptor channel, was added in the uptake medium. Lqh venom in the absence of heparin unexpectedly decreased the rate and the amount of $^{45}Ca^{2+}$ uptake. These results were explained by simultaneous increases in $^{45}Ca^{2+}$ release as well as $^{45}Ca^{2+}$ uptake by Lqh venom. Lqh venom itself increased the release of $^{45}Ca^{2+}$ as much as $^{45}Ca^{2+}$ release by $4\;{\mu}m\;InsP_3$, implying that Lqh venom also activates $InsP_3$ receptor, microsomal $Ca^{2+}$ release channel. Based on these results, we suggest that the Lqh venom consists of at least two components; one activates the $InsP_3$ receptor and the other avates the $Ca^{2+}-ATPase$. Currently we a investigating the chemical and electrophysiological properties of the active components of Lqh venom.

• Applied Biological Chemistry
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• v.42 no.2
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• pp.116-122
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• 1999

In order to characterize the property of $Ca^{2+}$ transport in plant cell, microsomes were prepared from the roots of tomato and microsomal $^{45}Ca^{2+}$ uptake was measured. When 1 mM vanadate, a selective inhibitor of P-type ATPases, 50 mM $NO_3^-$, a specific inhibitor of vacuolar $H^{+}-ATPase$, and both of these inhibitors were treated, the microsomal $^{45}Ca^{2+}$ uptakes were inhibited by 20, 33 and 47%, respectively. The inhibitory effects of these two inhibitors were investigated by using a protonophore, gramicidin. When the chemical gradient of $H^{+}$ was relieved by gramicidin, the uptake was decreased by 30%, implying the presence of $Ca^{2+}/H^+$ antiporter in the microsomal membrane. In the $^{45}Ca^{2+}$ uptake experiment, the effect of gramicidin was independent of vanadate-induced inhibition. However, when the activity of vacuolar $H^{+}-ATPase$ was inhibited by $NO_3^-$, the effect of gramicidin was severely decreased. Meanwhile, thapsigargin, a specific antagonist of ER/SR-type $Ca^{2+}-ATPase$, inhibited the microsomal $^{45}Ca^{2+}$ uptake and the maximum inhibitory effect was obtained at $10\;{\mu}M$. The effect of thapsigargin was blocked by $NO_3^-$ and gramicidin, but not by vanadate. These results imply that vanadate directly inhibits the activity of $Ca^{2+}-ATPase$; however, $NO_3^-$ and thapsigargin block the activity of $Ca^{2+}/H^+$ antiporter by inhibiting the vacuolar $H^{+}-ATPase$. In conclusion, the microsomal $^{45}Ca^{2+}$ uptakes are mediated by two major enzymes, $Ca^{2+}-ATPase$ and $Ca^{2+}/H^+$ antiporter in tomato root tissue.

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.115-123
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• 1994

To study bone resorption mechanism, effect of LPS on the $^{45}Ca$ release from fetal rat ulnae and radii, and effects of carbonic anhydrase inhibitors on the LPS-induced bone resorption in organ culture were studied. Ulnae and radii were removed from 19 day old fetal rats, prelabelled by subcutaneous injection of $200{\mu}Ci\;^{45}CaCl_2$ into their mother on the 17th day of gestation. Radioactivities of $^{45}Ca$ released into media were determined after 24, 48 and 72 hours. Effects of LPS and carbonic anhydrase inhibitors were observed by the ratio of $\%$ release of $^{45}Ca$ between paired control and experimental group. The observed results were as follows : 1. $LPS(1{\mu}g/ml)$ supplemented in media for 72hours increased the $^{45}Ca$ release significantly after 48 and 72 hours of culture and $LPS(10{\mu}g/m1)$ increased the $^{45}Ca$ release significantly after 72 hours of culture. 2. LPS-induced $^{45}Ca$ release was not inhibited significantly by 1mM sulfanilamide but inhibited significantly by 10mM sulfanilamide after 48 and 72 hours of culture. 3. LPS-induced $^{45}Ca$ release was not inhibited significantly by 0.1mM dichlorphenamide but inhibited significantly by 1mM dichlorphenamide after 48 and 72 hours of culture. 4. LPS-induced $^{45}Ca$ release was not inhibited significantly by 1mM acetazolamide but inhibited sighificantly by 5mM acetazolamide after 72 hours of culture.

• Journal of Food Hygiene and Safety
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• v.11 no.2
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• pp.83-87
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• 1996

The objective of this study is to investigate the direct effects of green tea catechins(GTC) on vascular smooth muscle tension and 45Ca2+ Uptake in rat aorta. The methods used in this study are isometric tension measurements using physiograph, Lanthanum method for 45Ca2+(2 uCi/ml) uptake measurement in rat aorta. GTC modified tension induced by 40 mM KCl or 1 uM norepinephrine in rat aorta. Low concentrations of GTC(<0.5mg/ml) increased tension by 40 mM KCl or 1 uM norepinephrine, individually. However, high conecentration of GTC(>0.5 mg/ml) inhibiited tension by 40 mM KCl or 1 uM norepinephrine, individually. GTC increased 45Ca uptake induced by 40 mM KCl in a dose-dependent manner. From these results, GTC has the dual actions in vascular smooth muscle in vitro. Low concentrations of GTC augments tension by K or norepinephrine. However, high concentrations of GTC inhibits tension by K or norepinephrine GTC may have Ca2+ channel activation, action, which may result in unphysiological vasodilation by Ca2+ overload in vascular smooth muscle.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.725-732
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• 1998

In order to elucidate the molecular mechanism of the intracellular $Ca^{2+}$ overload frequently reported from diabetic heart, diabetic rats were induced by the administration of streptozotocin, the membrane vesicles of junctional SR (heavy SR, HSR) were isolated from the ventricular myocytes, and SR $Ca^{2+}$ uptake and SR $Ca^{2+}$ release were measured. The activity of SR $Ca^{2+}-ATPase$ was $562{\pm}14$ nmol/min/mg protein in control heart. The activity was decreased to $413{\pm}30$ nmol/min/mg protein in diabetic heart and it was partially recovered to $485{\pm}18$ nmol/min/mg protein in insulin-treated diabetic heart. A similar pattern was observed in SR $^{45}Ca^{2+}$ uptakes; the specific uptake was the highest in control heart and it was the lowest in diabetic heart. In SR $^{45}Ca^{2+}$ release experiment, the highest release, 45% of SR $^{45}Ca^{2+}$, was observed in control heart. The release of diabetic heart was 20% and it was 30% in insulin-treated diabetic heart. Our results showed that the activities of both SR $Ca^{2+}-ATPase$ and SR $Ca^{2+}$ release channel were decreased in diabetic heart. In order to evaluate how these two factors contribute to SR $Ca^{2+}$ storage, the activity of SR $Ca^{2+}-ATPase$ was measured in the uncoupled leaky vesicles. The uncoupling effect which is able to increase the activity of SR $Ca^{2+}-ATPase$ was observed in control heart; however, no significant increments of SR $Ca^{2+}-ATPase$ activities were measured in both diabetic and insulin-treated diabetic rats. These results represent that the $Ca^{2+}$ storage in SR is significantly depressed and, therefore, $Ca^{2+}-sequestering$ activity of SR may be also depressed in diabetic heart.