Effects of dietary Ca2+ on erythrocyte Na(+)-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.
Fujito
K
K
Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan.
Yokomatsu
M
M
Ishiguro
N
N
Numahata
H
H
Tomino
Y
Y
Koide
H
H
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002136:Calcium, Dietary / Q000494:pharmacology*; D004912:Erythrocytes / Q000378:metabolism*; D006973:Hypertension / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012964:Sodium / Q000097:blood*
D002136:Calcium, Dietary; D012964:Sodium