Effect of high calcium diet on magnesium, catecholamines, and blood pressure of stroke-prone spontaneously hypertensive rats.
To test the effect of a high dietary calcium intake on blood pressure, we fed stroke-prone spontaneously hypertensive (SHR-SP) and Wistar-Kyoto rats (WKY) diets containing (a) 0.25% Ca/0.08% Mg, (b) 4.0% Ca/0.02% Mg, and (c) 4.0% Ca/0.08% mg, beginning at 6 weeks of age. SHR-SP and WKY rats receiving 4% Ca with the lower Mg content had lower blood pressures, hypomagnesemia, and hypomagnesuria, and grew poorly. SHR-SP receiving 4% Ca and the higher Mg diet had blood pressures no different from those of rats receiving the 0.25% Ca diet, in spite of having lower body weights. Rubidium flux studies in erythrocytes were not influenced by Ca or Mg in the diets. Plasma phosphate values were moderately reduced in rats receiving 4% Ca diets. Epinephrine and norepinephrine values were higher in SHR-SP than in WKY rats. Norepinephrine increased with stress in both strains, independent of diet. Epinephrine values were lower in SHR-SP receiving the 4% Ca diets and showed less of an increase with stress compared to SHR-SP receiving the 0.25% Ca diet. After 26 weeks of diets, SHR-SP and WKY rats were given 0.9% NaCl in their drinking water. NaCl increased blood pressure in SHR-SP irrespective of Ca content of the diet. These data suggest that a high Ca diet influences Mg homeostasis and adrenal medullary function in SHR-SP. Further, SHR-SP appear resistant to any blood pressure lowering effect of Ca irrespective of NaCl intake.
Luft
F C
FC
German Institute for High Blood Pressure Research, University of Heidelberg, Federal Republic of Germany.
Ganten
U
U
Meyer
D
D
Steinberg
H
H
Gless
K H
KH
Unger
T
T
Ganten
D
D
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000494:pharmacology; D002561:Cerebrovascular Disorders / Q000503:physiopathology; D004837:Epinephrine / Q000097:blood*; D008274:Magnesium / Q000008:administration & dosage / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood*; D011188:Potassium / Q000097:blood / Q000652:urine; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012413:Rubidium / Q000097:blood; D012964:Sodium / Q000097:blood / Q000652:urine; D012965:Sodium Chloride / Q000494:pharmacology
D002136:Calcium, Dietary; D012965:Sodium Chloride; D012964:Sodium; D008274:Magnesium; D012413:Rubidium; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine