• KOREAN JOURNAL OF CROP SCIENCE
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• v.12
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• pp.25-29
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• 1972

This experiment was carried out to investigate the role of Silicon accumlated in rice plant under different conditions of light and humidity, using radioisotopes Ca-45, Mn-54, and P-32. This results obtained in are as follows; 1. Light effect is more severe in phosphate uptake by rice plant than is calcium. Amounts of phosphate uptake in light condition is six times more than in dark conditions, while that of calcium is double. 2. Change of relative humidity affects calcium absorption and transport from root to shoot. It seems not to be influenced in phosphate and manganese uptake by relative humidity. 3. More uptake of each element Ca-45, P-32, or Mn-54 was found in the rice plant applied with silicic acid. It is considered that there must be some relationship between silicon content and ion uptake in rice plant. 4. The transport ratio of nutrient from root to shoot shows a specific pattern that calcium is approximately 1.0 manganese 0.5 and phosphate 0.2 respectively.

• 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.

• YAKHAK HOEJI
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• v.41 no.5
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• pp.666-671
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• 1997

We studied effects of genistein and tyrphostin, inhibitors of tyrosine kinase, on contractions induced by high $K^+$ and norepinephrine in rat aorta. Genistein $(10^{-6}{\sim}10^{-4}M)$ and tyrphostin ($(10^{-5}{\sim}10^{-4}M)$) inhibited high $K^+$ and norepinephrine-induced sustained contractions, respectively in a concentration-dependent manner. High $K^+$ and norepinephrine caused an increase in $^{45}Ca^{2+}$ uptake while $10^{-4}M$ genistein and tyrphostin inhibited the $K^+$ and norepinephrine-increased $^{45}Ca^{2+}$ uptake, respectively. These results show that inhibitor of tyrosine kinase blocks the voltage-and receptor-operated $Ca^{2+}$ channels in rat aorta, respectively.

• Korean Journal of Veterinary Research
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• v.39 no.2
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• pp.287-293
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• 1999

Isoeugenol, one of the phenylpropanoid derivatives has been known to inhibit the lipid peroxidation via scavenging effect on hydroxyl or superoxide radical production. We examined whether isoeugenol has a inhibitory effect against N-methyl-D-aspartate(NMDA)-, oxygen/glucose deprivation- and xanthine/xanthine oxidase(X/XO)-induced neurotoxicity or NMDA-induced $^{45}Ca^{+2}$ uptake elevation in primary mouse vertical cultures. We also evaluated whether isoeugenol exhibits inhibitory action on NMDA-induced convulsion in mice. Isoeugenol ($30{\sim}300{\mu}M$) attenuated NMDA- and X/XO-induced neurotoxicity by 11~85% and 83~92%, respectively. In the oxyge/glucose deprivation(60 min)-induced neurotoxicity, isoeugenol significantly(p<0.05) reduced by 32% at the maximal concentration. However, it failed to ameliorate NMDA-induced $^{45}Ca^{+2}$ uptake elevation. Isoeugenol(0.5g/kg, i.p.) delayed 6.5 times on the onset time of convulsion evoked by NMDA($0.1{\mu}g$) compared to that of control. These results suggest that the neuroprotective action of isoeugenol may be ascribed to the modulation of massive generation of reactive oxygen species(ROS) occurred during the ischemic or excitotoxic damage, not by directly affecting the NMDA receptor.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.115-121
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• 1987

A pot experiment was conducted to investigate the influence of Ca and Mg saturation ratios of soil on the uptake of Ca, Mg and K by rice plant. A silty loam soil was treated with $CaCl_2$ and $MgCl_2$ to obtain different degrees of Ca and Mg saturation. The studied ranges of Ca and Mg saturation ratios were 81:19, 70:30, 52:48, 55:45, and 31:69 in terms of the ratio of exchangeable Ca and Mg. Two levels of K application (90kg/ha, and 180kg/10a as $K_2O$) were also included in this study. The significant observation were summarized as follows. 1. When the Ca saturation of soil was dominant over Mg, the soil solution contained more Ca than Mg and vice versa. These led to the higher uptake of Ca by rice plant in Ca dominant soils and higher uptake of Mg in Mg dominant soils. 2. When the Ca and Mg saturation ratio was about equal, more Mg was released to soil solution leading to higher concentration of Mg in rice plant compare to that of Ca. 3. A trend was observed that the concentration of K in soil solution was lower in Mg dominant soils than in Ca dominant soils. This also resulted in the depressed uptake of K by rice plant under Mg dominant system when compare to Ca dominant system. 4. The increase application of K led to the increase in relative concentration of K to (Ca+Mg+K), and to the depression of divalent uptake by rice plant. However, it was observed that the degree of depression in uptake divalent by K application was more sensitive in case of Mg than that of Ca. 5. When viewed from grain yield of rice, it is pointed out that the optimum range of Ca to Mg ratio in soil may fall in the vicinity of 7:3. 6. Although K uptake by rice plant was influenced by the term of $AK^+/{\sqrt{A(Ca^{{+}{+}}+Mg^{{+}{+}})$ in soil solution, $AK^+$ itself was affected by the ratios of Ca:Mg in soil, as it were $AK^+$ value was decreased in Mg dominant soil than in Ca.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.529-535
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• 1997

The present study was aimed at investigating whether the vascular calcium regulation is altered in hypertension. Two-kidney, one clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt hypertension were made in rats, and their thoracic aortae were taken 4 weeks later. The isometric contractile response and calcium uptake of the endothelium-denuded aortic preparations were determined. Caffeine ($0.1{\sim}35\;mmol/L$) induced a greater contraction in 2K1C and DOCA-salt hypertension than in normotensive control. When the vascular calcium store was functionally-depleted by a repeated exposure to caffeine, it took longer to reload the store and to resume the initial contraction force in response to caffeine in both 2K1C and DOCA-salt hypertension. The vascular $^{45}Ca$ uptake following the functional depletion of the cellular store was also greater in both models of hypertension than in control. Ryanodine, calcium channel activator of the sarcoplasmic reticulum, attenuated the restoration of caffeine-induced vascular contraction, which was not affected by either 2K1C or DOCA-salt hypertension. Nifedipine, an L-type $Ca^{2+}$ channel blocker, attenuated the restoration of caffeine-induced contraction, which was not affected by DOCA-salt hypertension, but was more pronounced in 2K1C hypertension. Nifedipine also diminished the vascular $^{45}Ca$ uptake, which was not affected by DOCA-salt hypertension, but was more pronounced in 2K1C hypertension. Ouabain, a $Na^+,\;K^+-ATPase$ inhibitor, increased the caffeine-induced contraction by a similar magnitude in control and 2K1C hypertension, which was, however, markedly attenuated in DOCA-salt hypertension. Ouabain enhanced the vascular $^{45}Ca$ uptake, the degree of which was not affected by 2K1C hypertension, but was markedly attenuated in DOCA-salt hypertension compared with that in control. Cyclopiazonic acid, a selective inhibitor of $Ca^{2+}-ATPase$ of the sarcoplasmic reticulum, attenuated the restoration of caffeine-induced contraction, which was not affected by 2K1C hypertension, but was more marked in DOCA-salt hypertension. These results suggest that the increased vascular calcium storage may be attributed to an enhanced calcium influx in 2K1C hypertension, and to an impaired $Na^+-K^+$ pump activity of the cell membrane and subsequently increased calcium pump activity of the cellular store in DOCA-salt hypertension.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.67-73
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• 1994

Na-Ca exchange transports calcium ion either into (reverse mode Na-Ca exchange) or out of the cell (forward mode Na-Ca exchange) according to the direction of driving force produced by the changes in ratio of intra- and extra-cellular Na concentrations. Thus, Na-Ca exchange is regarded as the regulator of myocardial contraction. However, the existence of reverse mode Na-Ca exchange and its role in myocardial contraction is still questioned. Present study was performed to identify the presence of reverse mode Na-Ca exchange and its possible involvement in the regulation of myocardial contraction in rat heart. Using the left atria of rat, contraction was induced by electrical field stimulation (EFS, 0.5 msec duration and supramaximal voltage). Changing of the stimulation frequencies from resting 4 Hz to 0.4, 1 or 8 Hz caused typical negative staircase effect in twitch tension, but $^{45}Ca$ uptake showed bimodal increase. When the stimulation frequency was abruptly changed from 4 Hz to 0.4 Hz the atrial twitch tension showed three phased-enhancement, that is, the initial rapid increase (the first phase) followed by rapid decrease (the second phase) and stabilization (the third phase). $^{45}Ca$ uptake was equivalent to tension, i.e. initial significant increase in first 30 second and then decrease. Benzamil treatment abolished the first phase of increase in a dose dependent manner from $10^{-5}\;to\;3{\times}10^{-4}M.$ Bay k 8644 $(3{\times}10^{-5}M)$ treatment enhanced the inotropy induced by frequency reduction and abolished the second and third phase decreases. Benzamil treatment also suppressed the contraction stimulated by Bay K 8644. Although the contraction at 4 Hz stimulation was completely abolished by verapamil $3{\times}10^{-5}\;M$ pretreatment, the contraction reappeared as soon as the stimulation frequency was changed into 0.4 or 1 Hz and interstingly,$^{45}Ca$ uptake were significantly higher than no treatment. From these results, it is concluded that reduction of stimulation frequency causes calcium influx by the reverse mode Na-Ca exchange, resulting in initial rapid increase of twitch tension. then it turns into forward mode exchange to efflux the calcium, resulting in decrease of the twitch tension in left atria of rat.

• Archives of Pharmacal Research
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• v.17 no.4
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• pp.226-230
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• 1994

The characteristics of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release as factors controlling neural activities in the hypothalamus which is an important regulatory site for cardiovascular function wre studied. Two groups of animals : male spontaneously hyperterisive rat (SHR) and age-matched nomotensive wistar rat (NW) were used in this study. Animals at 4, 6 and 16 weeks of age were sacrificed by decapitiation and the hypothalamus was dissected out. Voltage-dependent calcium uptake and norepinephrine release were determined from hypothalamic synaptosomes either in low potassium (5 mM) or high potassium (41 mM) stimulatory conditions by using ^{45}Ca$ isotope and HPLC-ECD techniques. Degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release evoked by calcium uptake in the hypothalamus of prehypertensive phase (4 weeks old) of SHR were significantly smaller than those in NW of the same age. However, in the developmental phase (6 weeks old) and the established phase (16 weeks old) of hyperrtension in SHR, degrees of voltage-dependent ^{45}Calcium$ uptake and norepinephrine release were similar to those of age-matched normotensive wistae eats. These data imply that the deficit in hypothalamic norepinephrine release might be an important underlying factor for the development of hypertension in SHR.

• Proceedings of the Korean Society of Crop Science Conference
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• 2004.04a
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• pp.68-69
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• 2004

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.13-21
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• 1996

Intracellular calcium concentration ($[Ca^{2+}]_i$) may play a crucial role in a variety of neuronal functions. Here we report that in primary culture of mouse cerebellar granule cells nicotinic acetylcholine receptors (nAChRs) are expressed in a specific developmental stage and involved in the regulation of intracellular calcium homeostasis. Nicotine-mediated calcium responses were measured using $^{45}Ca^{2+}$ or fluorometrically using the calcium-sensitive fluorescent dye fura-2. Maximal uptake of $^{45}Ca^{2+}$ evoked by nicotine in mouse cerebellar granule cells were revealed $8{\sim}12$ days in culture. In contrast, nicotine did not alter the basal $^{45}Ca^{2+}$ uptake in cultured glial cells. In cerebellar granule cells nicotine-evoked $^{45}Ca^{2+}$ uptake was largely blocked by the NMDA receptor antagonists. Glutamate pyruvate transaminase (GPT). which removes endogenous glutamate, also prevented nicotine effects, implying the indirect involvement of glutamate in nicotine-mediated calcium responses. Fluorometric studies using fura-2 showed two phases of nicotine-evoked $[Ca^{2+}]_i$ rises: the initial rising phase and the later plateau phase. Interestingly, the NMDA receptor antagonists and GPT appeared to inhibit only the later plateau phase of nicotine-evoked $[Ca^{2+}]_i$ rises. The present results imply that nicotine mediated $^{45}Ca^{2+}$ uptake and $[Ca^{2+}]_i$ rises are attributed to the calcium fluxes through both nAchRs and NMDA receptors in a time-dependent manner. Consequently, nAChRs may play an important role in neuronal development by being expressed in a specific developmental stage and regulating the intracellular calcium homeostasis.