Document Detail

Dietary calcium decreases blood pressure without decreasing renal vascular resistance or altering the response to NO blockade.
MedLine Citation:
PMID:  9422336     Owner:  NLM     Status:  MEDLINE    
Many vasoactive elements are involved in the elevation of blood pressure in spontaneously hypertensive rats (SHR). Elevated dietary calcium has been observed to reduce blood pressure in SHR. This study investigates interactions among dietary calcium, renal vascular resistance (RVR), elevation of blood pressure and effects of norepinephrine and nitric oxide synthesis. We completed a series of experiments on two groups each (fed low, 0.1% and high, 2.0% dietary calcium, respectively) of 9-week-old Wistar Kyoto (WKY), 9-week-old and 6-week-old SHR. Although 9-week-old SHR had elevated baseline blood pressure compared to 9-week-old WKY and also compared to 6 week-old SHR, there was no corresponding elevation in baseline RVR. All SHR fed high calcium diets had lower blood pressure compared to low calcium diets, and there was no corresponding reduction in RVR. WKY controls' blood pressure and RVR were unaffected by dietary calcium levels. In all hypertensive rats the blood pressure and renal vascular resistance were elevated by N(G)-nitro-L-arginine methylester (L-NAME), but the dietary differences were sustained. Blood pressure of WKY was unaffected by the low dose of L-NAME. The increase in RVR to L-NAME was greater in SHR than in controls. The renal vascular response to norepinephrine was related to diet in older SHR, but smaller and unrelated to diet in younger SHR. Following L-NAME, WKY had greater responses to norepinephrine than 9-week-old SHR. We conclude that noradrenergic vasoconstriction is enhanced in the adult SHR, especially in the absence of high calcium diet. Alterations in NO synthesis may effect the norepinephrine response.
J C Passmore; D C Hatton; D A McCarron
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of laboratory and clinical medicine     Volume:  130     ISSN:  0022-2143     ISO Abbreviation:  J. Lab. Clin. Med.     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1998-01-27     Completed Date:  1998-01-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375375     Medline TA:  J Lab Clin Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  627-34     Citation Subset:  AIM; IM    
Department of Physiology and Biophysics, University of Louisville School of Medicine, KY 40292, USA.
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MeSH Terms
Age Factors
Blood Pressure* / drug effects
Calcium, Dietary / pharmacology*
Hypertension / physiopathology
Kidney / blood supply*
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / physiology*
Norepinephrine / pharmacology
Rats, Inbred SHR
Regional Blood Flow
Vascular Resistance / drug effects
Grant Support
Reg. No./Substance:
0/Calcium, Dietary; 10102-43-9/Nitric Oxide; 50903-99-6/NG-Nitroarginine Methyl Ester; 51-41-2/Norepinephrine

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