Effect of dietary calcium on the development of hypertension and hypertensive vascular lesions in DOCA-salt and two-kidney, one clip hypertensive rats.

OBJECTIVE

To examine the effect of modest changes in dietary calcium on systolic blood pressure (SBP) and myocardial and renal vascular lesions in Sprague-Dawley rats.

DESIGN

Regular- (0.4%, by weight), high- (0.8%) or low-calcium (0.24%) diets were fed to normotensive control, deoxycorticosterone acetate (DOCA)-salt and two-kidney, one clip (2-K, 1C) hypertensive rats for 8 weeks.

METHODS

Tail-cuff SBP and metabolic balance were measured once a week. At the end of the study the kidneys and hearts were collected for histological study.

RESULTS

Dietary calcium had no effect on SBP in the DOCA-salt rats, but loading with calcium accelerated the rise in SBP in 2-K,1C rats (P < 0.01, high- versus regular-calcium diet). The high-calcium diet reduced the percentage medial area of intramyocardial arteries in the DOCA-salt and 2-K,1C hypertensive rats. The DOCA-salt rats on the low-calcium diet had a higher renal vascular lesions score than those on the regular- or high-calcium diet (P < 0.05).

CONCLUSIONS

A high-calcium diet appears to prevent intramyocardial vascular wall thickening in DOCA-salt and 2-K,1C hypertensive rats, and a low-calcium diet aggravates renal vascular lesions in DOCA-salt hypertensive rats. These effects are not related simply to changes in blood pressure.