• Journal of Nutrition and Health
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• v.35 no.8
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• pp.840-847
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• 2002

This study explored the effect of dietary levels of Na and Ca on spontaneously hypertensive rats (SHR). SHR were randomly divided into 5 groups and fed a high fat/cholesterol diet containing three levels of Na (0.05, 0.1, 1.5%) and Ca (0.1, 0.5, 1.5%) for 9 weeks. Body weight gain was not influenced by dietary intake but water intake significantly increased in high Na supplementation. Systolic blood pressure was not influenced by dietary Na and Ca levels but was decreased by dietary low Na/high Ca levels at 9 weeks. Angiotensin-II level was affected by dietary Na level but not by Ca levels. Plasma Ca, Mg, K and Na levels were in the normal range regardless of dietary Na and Ca levels. Weight, and K and Na contents of the heart and kidney were not significantly different among those with different dietary Na and Ca levels. Ca and Mg contents of the heart and kidney were significantly higher in the normal Na/normal Ca group. Ca and Mg in the feces were higher in those with high Ca intake. Na in the feces was higher in those with high Na intake. Therefore, Na and Ca had different mechanisms in the hypertension/hyperlipidemia models, respectively. And we suggested that Mg must be supplemented when Ca intake was high because Mg excretion was increased by Ca supplementation.

• Journal of Nutrition and Health
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• v.34 no.4
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• pp.409-416
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• 2001

In order to evaluate the effect of habitual Na and Ca intake on blood pressure regulation, we measured the habitual dietary intakes of Na and Ca, urinary excretion of Ca, Na and K, and plasma level of renin activity, aldosterone, and indices of Ca metabolism in 27 untreated hypertensive women and 30 age-matched normal women on a free diet. Hypertensive and total subjects were divided into four groups according to habitual dietary intakes of Na and Ca as low Na-low Ca(LNLC), low Na-high Ca(LNHC), high Na-low Ca(HNLC), and high Na-high Ca(HNHC). HNLC hypertensive group showed the lowest level of plasma renin activity, 25-(OH) Vit D$_3$, calcitonin and serum total Ca, and presented the highest level of PTH and urinary excretions of Na/K and Ca/Cr. There were no significant difference in plasma level of aldosterone and urinary excretion of Na and K among four hypertensive groups. When all subjects were divided into four groups according to the same method, HNLC group showed the highest level of blood pressure with no statistical significance and the lowest level of calcitonin and total serum Ca. The above results indicated that renin-aldosterone system and Ca regulating hormone has a mutual relationship in hypertension. Na and Ca may interact each other, rather than affecting independently blood pressure control. As a result, considering the fact that daily balance of Na and Ca intakes affects Na and Ca regulating hormones and urinary excretion of Na and Ca, it may be involved in blood pressure control. These results suggest that maintaining an adequate intake of Ca with less intake of Na may prevent from the risk of hypertension. (Korean J Nutrition 34(4) : 409~416, 2001)

• 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 Nutrition and Health
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• v.28 no.4
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• pp.309-320
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• 1995

The purpose of this research was to investigate the effect of calcium levels(50, 100 and 200% of requirement) on metabolism of Ca, Na and K in Young and adult female rats for 3 weeks. There was no significant difference in feed intake, body weight gain and feed efficiency ratio among the groups of different Ca intake level. Serum Na level of high-Ca group was significantly lower than that of low-Ca or normal-Ca group in Young rats. There was no significant difference in liver Ca and K contents among the groups of different Ca intake levels. But, Na content in liver was decreased by the increase of dietary Ca intake. Ca content in kidney of high-Ca group in young rats and normal-Ca group in adult rats were significantly higher than those of other groups. Na content in kidney of low-Ca group was lower than those of normal-Ca and high-Ca groups. Urinary excretions of Na and K and fecal excretion of Ca were increased by the increase of dietary Ca intake. But, fecal excretions of Na and K were not affected by dietary Ca intake. According to this study, it was found that the high Ca consumption promotes excretions of fecal Ca and urinary Na and K in rats. The study verifies the need for more study on the interrelationship among Ca, Na and K metabolism and bood pressure.

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.237-252
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• 1989

Effect of a $Na^+$ gradient on $Ca^{2+}$ uptake was studied in isolated sarcolemmal vesicles of cat ileal longitudinal muscle. $Ca^{2+}$ uptake was markedly stimulated in the presence of an outwardly directed $Na^+$ gradient. External $Na^+$, monensin and A23187 abolished the $Na^+-dependent$ $Ca^{2+}$ uptake. Monovalent cations such as $K^+$, $Li^+$, $Rb^+$, $Cs^+$ and choline could not substitute for $Na^+$ in enhancement of $Ca^{2+}$ uptake. Divalent cations such as $Ba^{2+}$, $Sr^{2+}$, $Mn^{2+}$ and $Cd^{2+}$ but not $Mg^{2+}$ inhibited the $Na^+-dependent$ $Ca^{2+}$ uptake. Increase in external pH in the range of 6.0 to 8.0 stimulated the $Na^+-dependent$ $Ca^{2+}$ uptake. Amiloride inhibited the $Na^+-dependent$ $Ca^{2+}$ uptake at concentrations above 0.5 mM, whereas diltiazem or vanadate did not. The apparent Km of the $Na^+-dependent$ $Ca^{2+}$ uptake for $Ca^{2+}$ was 18.2 ${\mu}M$ and apparent Vmax was 689.7 pmole/mg protein/5 sec. Kinetic analysis of the $Na^+-dependent$ $Ca^{2+}$ uptake showed a noncompetitive interaction between internal $Na^+$ and external $Ca^{2+}$. The dependence of $Ca^{2+}$ uptake on internal $Na^+$ showed sigmoidal kinetics and Hill coefficient for internal $Na^+$ was 2.52. Inside positive membrane potential generated by imposing an inwardly directed $K^+$ gradient and valinomycin significantly stimulated the $Na^+-dependent$ $Ca^{2+}$ uptake. These results indicate that a $Na^+-Ca^{2+}$ exchange system exists in the sarcolemmal membranes isolated from cat ileal longitudinal muscle and it might operate as an electrogenic process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.6
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• pp.267-272
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• 2006

A series of $Sr_{1-x}Ca_xGa_2S_4:Ce,Na$ phosphors have been synthesized by solid-state reaction. The photoluminescence and structural properties of $Sr_{1-x}Ca_xGa_2S_4:Ce,Na$ have been examined. The $Sr_{1-x}Ca_xGa_2S_4:Ce,Na$ phosphors have a strong absorption at 400 nm, which is the emission wavelength of a violet light emitting diode (LED). The emission peaks of $SrGa_2S_4:Ce,Na$are located at 448 nm and 485 nm. The partial replacement of Sr by Ca in $Sr_{1-x}Ca_xGa_2S_4:Ce,Na$ causes a red shift of emission wavelengths. The $Sr_{1-x}Ca_xGa_2S_4:Ce,Na$ can be used as blue emitting phosphors pumped by the violet LED for fabricating the multi-band white LED.

• The Korean Journal of Pharmacology
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• v.17 no.1 s.28
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• pp.1-8
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• 1981

The $Na^+$-induced calcium release and the effect of sodium on the transmitochondrial calcium flux were observed in mitochondria isolated from pig ventricular myocardium by Milipore filtration technique using radioisotope $^{45}Ca$. The release of calcium from cardiac mitochondria was induced by small amount of sodium, and was promoted by increasing sodium concentration in the incubation medium. The extent of the $Na^+$-induced calcium release was much greater in the absence of extramitochondrial calcium than in the presence of calcium. At steady state of calcium binding on the mitochondrial membrane unidirectional calcium influx was inhibited by sodium and unidirectional calcium efflux was increased., From the above results, it was suggested that calcium might be released from cardiac mitochondria in exchange with sodium through the mediation of the postulated '$Na^+/Ca^{++}$ exchange' mechanism.

• Journal of the Mineralogical Society of Korea
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• v.15 no.4
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• pp.243-257
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• 2002

Ca-type and Na-type bentonites show the great difference of some physicochemical properties. Na exchanged bentonite is mainly used for the foundry and construction materials in domestic utilization. This study tries to identify in detail the differences of some physicochemical properties and thermal properties between Ca-type and Na-type bentonites. Also the adsorption behavior and interlayer expansion for the HDTMA (Hexadecyltrimethylammonium) exchanged and CP (Cetylprydinium) exchanged Ca-type and Na-type bentonites were compared. Na-type bentonite shows the strong alkaline property, high viscosity and swelling compared to Ca-type bentonite. However, two types are very similar for the cation exchange capacity and MB (Methylene Blue) adsorption. The decomposition of adsorbed and interlayer water of Na-type bentonite is caused in the lower temperature than Ca-type bentonite. And Ca-type bentonite shows the decomposition of structural water in the lower temperature than Na-type bentonite. The interlayer expansion of montmorillonite resulted to the intercalation of HDTMA and CP into bentonite is so strongly caused from 12～15 $\AA$ to $40\AA$ (basal spacing). HDTMA-bentonite is almost expanded to $37～38\AA$ when 200% CEC equivalent amount of HDTMA is added, and CP-bentonite is fullly expanded to 40 $\AA$ in the 140% CEC equivalent amount of CP It means that CP causes the stronger interlayer expansion of montmorillonite and easier adsorption than HDTMA. Adsorption behaviors of CP into bentonite is so stable and continuously sorbed in the proportion to the treatment of amount until 200% of the CEC equivalents. CP-bentonite shows the same adsorption behavior regardless of Ca-type or Na-type montmorillonite.

• The Korean Journal of Physiology
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• v.28 no.2
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• pp.159-167
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• 1994

The contraction of rabbit basilar artery was examined as a function of changes in the $Na^+$ electrochemical gradient in order to determine the contribution of $Na^+/Ca^{2+}$ exchange to the modulation of contractility. Ouabain $(10^{-5}\;M)$ or $K^+-free$ Tyrode solution caused an increase in tonic tension even in the presence of a $Ca^{2+}$ channel blocker $(10^{-6}\;M\;verapamil)$ and an ${\alpha}-receptor$ blocker $(10^{-5}\;M\;phentolamine)$. After treatment with ouabain $(10^{-5}\;M)$, contractions were augmented by reduction of external $Na^+$ concentration. The longer the treatment with ouabain $(10^{-5}\;M)$ was, the larger the amplitude of $Na^+-free$ contracture was. $Na^+-free$ contracture wag induced by either substitution of equimolar Tris for $Na^+$ or substitution of equimolar $Li^+\;for\;Na^+$. The competition between $Na^+\;and\;Ca^{2+}$ for the $Na^+/Ca^{2+}$ exchange carrier would exist, because it was observed that contractility was dependent on the $Na^+$ electrochemical gradient or the extracellular $Ca^{2+}$ concentration (2 mM, 4 mM). Ryanodine $(10^{-7}\;M)$, the blocker of intracellular $Ca^{2+}$ release from the sarcoplasmic reticulum, did not suppress the development of $Na^+-free$ contracture. The contractile response to norepinephrine $(10^{-6}\;M)$ was augmented by reducing the extracellular $Na^+$ concentration. The relaxation rate from caffeine-induced contraction was dependent on the extracellular $Na^+$ concentration (0 mM, 140 mM). From the above results, it could be suggested that $Na^+/Ca^{2+}$ exchange can move $Ca^{2+}$ either into or out of rabbit basilar arterial smooth muscle. $Ca^{2+}$ entry or extrusion is dependent upon the $Na^+$ electrochemical gradient. $Na^+/Ca^{2+}$ exchange plays a significant role in the regulation of contractility in rabbit basilar arterial smooth muscle.

• Journal of Nutrition and Health
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• v.32 no.6
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• pp.671-680
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• 1999

In order to investigate the relationship between plasma renin activity and metabolism of Ca and Na in blood pressure, the habitual dietary intakes of Na and Ca urinary excretion of Ca, Na and K, and plasma level of renin activity, aldosterone, and indices of Ca metabolism were measured in 27 untreated hypertensive women and 30 age-matched normal women on a free diet. Hypertensive subjects were classified into high renin hypertensive (HH), medium renin hypertensive(HM) and low renin showed no significant difference among normotensive, LH, MH and HM groups. It appeared that 25-(OH) Vit D3 level of HH group was significantly higher than LH group(p<0.05). There was significant difference in habitual intake of Ca between normotensive and LH groups. However, habitual intake of Na showed no significant difference among normotensive, LH, MH and HH group. Positive correlation of systolic and diastolic blood pressure with PTH(r=0.324, r=0.375) and urinary Ca(r=0.496, r=0.278) and a negative correlation of systolic blood pressure with habitual Ca intake(r=-0.371) existed(p<0.05). A relative magnitude of factors affecting hypertension was analyzed by multiple regression analysis. Overall results about relative influence of independent variables to dependent variable (systolic blood pressure) indicated that urinary Ca was the higher correlation in all subjects(p<0.0001), followed by age and aldosterone. PTH showed a significant correlation for relative influence on diastolic blood pressure in all subjects. The above results indicated that renin-aldosterone system and Ca regulating hormone had a mutual relationship in hypertension.