Altered aortic reactivity and lowered blood pressure associated with high calcium intake
Bukoski, R.D.; McCarron, D.A.
American Journal of Physiology 251(5 Pt 2): H976-H983
1986
ISSN/ISBN: 0002-9513 PMID: 3777204 Document Number: 285127
The hypothesis that dietary calcium changes functional properties of aortic smooth muscle in the spontaneously hypertensive (SH) rat was tested. At 6 weeks old, Wistar Kyoto (WKY) and SH rats were given a control diet with 1% Ca. The experimental SH group received a diet with 2% Ca. After 8 or 15 weeks on the diets, aortic rings were prepared for estimation of passive elastic properties and isometric force development. Differences in blood pressure (BP) were not apparent until after 8 weeks when the BP of SH rats on 2% Ca was 10 to 15 mmHg lower than that of SH rats on 1% Ca. After 8 weeks, when the BP effect first emerged, no significant difference in aortic properties was observed between the SH groups. After 15 weeks, aorta of SH rats on 2% Ca was more compliant than that of SH rats on 1% Ca and between 8 and 15 weeks the sensitivity to KCl decreased in aorta from WKY rats and SH rats on 2% Ca, but not in that from SH-1% Ca group. Between 8 and 15 weeks, a significant decrease in response to a Ca2+ challenge after removal of K+ and Ca2+ occurred in aorta of the SH rats on 2% Ca, but not in the control diet groups, indicating that a decrease in aortic reactivity was present in the Ca2+-supplemented SH rats.