Effect of oral calcium on blood pressure response in salt-loaded borderline hypertensive patients.
To clarify the mechanism of the antihypertensive effect of oral calcium loading, we studied the effect of low versus high calcium intake on salt-induced blood pressure elevations in patients with borderline hypertension. After a 7-day period of dietary salt restriction (50 meq/day), 27 patients were placed on a high salt (300 meq/day), low calcium (250 mg/day) diet for 7 days; 14 of these patients were given 2,160 mg/day of supplementary calcium (Ca group), and 13 patients were given placebo (non-Ca group). With a high salt intake, the percent increase in mean blood pressure was smaller in the Ca group than in the non-Ca group (+2.85 +/- 1.22% vs. +8.63 +/- 1.66%, respectively, p less than 0.01). The Ca group showed a smaller weight gain (p less than 0.05) and a greater urinary excretion of sodium (p less than 0.005) than the non-Ca group. In the Ca group, but not in the non-Ca group, high salt intake resulted in an increase in intraerythrocyte magnesium content (p less than 0.01), which was correlated inversely with the salt-induced changes in mean blood pressure (r = -0.54, p less than 0.05). While the increase in cellular magnesium was greater in the Ca group, the changes in red blood cell sodium and sodium/potassium ratio were not different between the two groups. The results suggest that oral calcium supplementation may prevent a rise in blood pressure in patients on a high salt, low calcium diet by attenuating the sodium retention.(ABSTRACT TRUNCATED AT 250 WORDS)
Saito
K
K
Department of Internal Medicine, Hidaka Hospital, Hyogo, Japan.
Sano
H
H
Furuta
Y
Y
Fukuzaki
H
H
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000008:administration & dosage*; D002136:Calcium, Dietary / Q000008:administration & dosage; D004039:Diet, Sodium-Restricted; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000178:diet therapy / Q000503:physiopathology*; D008274:Magnesium / Q000097:blood; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood; D012982:Sodium, Dietary / Q000008:administration & dosage*
D002136:Calcium, Dietary; D012982:Sodium, Dietary; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium