Effects of Dietary Calcium on Erythrocyte Sodium Ion Transport Systems in Spontaneously Hypertensive Rats

1. The purpose of this study was to determine the effect of dietary Ca2+ intake on blood pressure and erythrocyte Na+ transport in spontaneously hypertensive rats. 2. Spontaneously hypertensive rats and Wistar-Kyoto rats were fed diets with three different Ca2+ contents, 0.1% (low-Ca2+ diet), 0.6% (normal-Ca2+ diet) and 4.0% (high-Ca2+ diet), between 6 and 20 weeks of age. At 20 weeks of age, the levels of erythrocyte Na+ efflux, as well as Na+ and K+ contents in erythrocytes, were measured. 3. On the low-Ca2+ diet, spontaneously hypertensive rats showed an enhancement of hypertension. Conversely, on the high-Ca2+ diet, they showed an attenuation of the increase in blood pressure. Spontaneously hypertensive rats had a lower erythrocyte Na+ content and increased activity of the Na+ pump at higher levels of dietary Ca2+. Passive Na+ permeability and Na+-K+ co-transport were similar in spontaneously hypertensive rats on the low-, normal- and high-Ca2+ diets. There were no significant differences in blood pressure and in Na+ pump activity in WKY on the three different diets. 4. It is concluded that dietary Ca2+ might affect the regulation of blood pressure in spontaneously hypertensive rats by changing the activity of Na+ pump in the cell membrane.

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Influence of dietary calcium on sodium and calcium intake of spontaneously hypertensive rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1992.262.3.r370 ◽

1992 ◽

Vol 262 (3) ◽

pp. R370-R381 ◽

Cited By ~ 3

Author(s):

M. G. Tordoff

Keyword(s):

Calcium Intake ◽

Spontaneously Hypertensive Rats ◽

Salt Intake ◽

Dietary Calcium ◽

Hypertensive Rats ◽

Deficient Diet ◽

Spontaneously Hypertensive ◽

High Salt Intake ◽

High Calcium ◽

Wistar Kyoto

Spontaneously hypertensive rats (SHRs) fed nutritionally complete diets voluntarily ingest more calcium and more NaCl solution than do their normotensive Wistar-Kyoto (WKY) controls. SHRs also have several anomalies in calcium metabolism. Given that calcium availability modulates NaCl intake of other rat strains, we examined whether sodium and calcium intake of the SHR was unusually responsive to manipulations of dietary calcium. In three experiments, groups of SHRs and WKYs ate diets differing in calcium content (0-1,000 mmol/kg) and drank solutions of sodium (50 and 300 mM NaCl or 50 mM sodium lactate) and/or calcium (50 and 110 mM calcium lactate or 50 mM CaCl2). Relative to WKYs, SHRs fed calcium-deficient diet (0 mmol Ca2+/kg) drank the same amount or less calcium solution, drank more NaCl, and increased NaCl intake more rapidly when the diet was first introduced. SHRs fed diets sufficient for normal growth (50-1,000 mmol Ca2+/kg) drank consistently more calcium and sodium solution than did WKYs. However, NaCl intake of SHRs was decreased by high-calcium diets, whereas NaCl intake of WKYs was not. Taken together, these results suggest that a mechanism dependent on the availability of calcium is at least partially responsible for the high salt intake of the SHR.

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B11 Dietary calcium improves bone mineral density (BMD) and lowers blood pressure (BP) in spontaneously hypertensive rats (SHR)

American Journal of Hypertension ◽

10.1016/s0895-7061(97)88998-4 ◽

1997 ◽

Vol 10 (4) ◽

pp. 96A

Author(s):

C ROULLET

Keyword(s):

Bone Mineral Density ◽

Blood Pressure ◽

Bone Mineral ◽

Spontaneously Hypertensive Rats ◽

Dietary Calcium ◽

Hypertensive Rats ◽

Mineral Density ◽

Spontaneously Hypertensive

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Intra-Erythrocyte Sodium and (Na+,K+-Activated)-ATPase Concentration and Urinary Aldosterone Excretion in Spontaneously Hypertensive Rats

Clinical Science ◽

10.1042/cs0600229 ◽

1981 ◽

Vol 60 (2) ◽

pp. 229-232 ◽

Cited By ~ 13

Author(s):

G. Berglund ◽

L. Sigström ◽

S. Lundin ◽

B. E. Karlberg ◽

H. Herlitz

Keyword(s):

Spontaneously Hypertensive Rats ◽

Sodium Concentration ◽

Intracellular Sodium ◽

Hypertensive Rats ◽

Spontaneously Hypertensive ◽

Wistar Kyoto Rats ◽

Significant Difference ◽

Intracellular Sodium Concentration ◽

Erythrocyte Sodium ◽

Wistar Kyoto

1. Intra-erythrocyte sodium, potassium, ATP and (Na+,K+-activated)-ATPase concentrations and urinary aldosterone excretion were compared in 3-month-old spontaneously hypertensive rats (n = 11) and normotensive Wistar-Kyoto control rats (n = 11). 2. Spontaneously hypertensive rats exhibited significantly higher intra-erythrocyte sodium concentration (5.5 ± 1.3 vs 4.0 ± 1.1 mmol/l of erythrocytes, P < 0.01). No significant difference was found in intra-erythrocyte potassium, ATP or (Na+,K+-activated)-ATPase concentration. 3. Mean urinary aldosterone excretion was significantly lower in spontaneously hypertensive rats (66.3 ± 6.5 pmol/24 h) than in Wistar-Kyoto rats (90.5 ± 10.6 pmol/24 h, P < 0.01). No significant relationship between urinary aldosterone and intra-erythrocyte sodium concentration was found in spontaneously hypertensive or Wistar-Kyoto rats or in the pooled group. 4. These results are thus consistent with previous findings of an increased intracellular sodium concentration in spontaneously hypertensive rats, but do not support the hypothesis that aldosterone is a dominant regulator of intracellular sodium concentration.

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