Dietary Ca2+ prevents NaCl-sensitive hypertension in spontaneously hypertensive rats via sympatholytic and renal effects.
NaCl-sensitive spontaneously hypertensive rats (SHR-S) were used to test the hypotheses that dietary Ca2+ supplementation 1) prevents NaCl-sensitive hypertension via a sympatholytic mechanism, and 2) increases diuretic and natriuretic responses to acute volume loading. SHR-S and control WKY rats were begun on one of four diets at age 8 wk: control, high NaCl, high Ca2+, or high NaCl and high Ca2+. In SHR-S, dietary Ca2+ supplementation prevented the NaCl-induced increases in blood pressure and plasma norepinephrine concentrations, the reductions in anterior hypothalamic norepinephrine stores and turnover, and the secondary increases in alpha 2 adrenoceptor number. Thus, Ca2+ prevented NaCl-sensitive hypertension in SHR-S by increasing noradrenergic input to the anterior hypothalamus. High-NaCl-fed SHR-S had impaired diuretic and natriuretic responses to an isotonic volume load; Ca2+ enhanced the ability of these animals to adjust fluid volume rapidly via diuresis and natriuresis. This alteration in renal function may contribute to the hypotensive effect of a high Ca2+ diet in NaCl-sensitive hypertension.
Oparil
S
S
Department of Medicine, University of Alabama, Birmingham 35294.
Chen
Y F
YF
Jin
H K
HK
Yang
R H
RH
Wyss
J M
JM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D003000:Clonidine / Q000008:administration & dosage / Q000494:pharmacology; D004231:Diuresis / Q000187:drug effects; D006973:Hypertension / Q000209:etiology / Q000517:prevention & control*; D007032:Hypothalamus, Anterior / Q000187:drug effects* / Q000378:metabolism; D007668:Kidney / Q000187:drug effects*; D008297:Male; D008845:Microinjections; D009318:Natriuresis / Q000187:drug effects; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012965:Sodium Chloride / Q000008:administration & dosage / Q000009:adverse effects*
D002136:Calcium, Dietary; D012965:Sodium Chloride; D003000:Clonidine; D009638:Norepinephrine