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High‐Calcium Diet in Spontaneously Hypertensive Rats: Intervention with Calcium Antagonist Verapamil
Author(s) -
Saelens David A.,
Zawada Edward T.,
Peterson Jennifer,
Lembke Jeanie M.
Publication year - 1993
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1993.tb04666.x
Subject(s) - verapamil , calcium , endocrinology , medicine , blood pressure , calcium channel blocker , antagonist , chemistry , receptor
A number of studies have shown an antihypertensive effect for high‐calcium diets, but others have found no effect or, even a prohypertensive effect. Because of these disparate results, studies were conducted in spontaneously hypertensive rats (SHR) fed either a normal calcium diet (1.0% calcium) or a high‐calcium diet (4.0% calcium) with or without verapamil HCl (50 mg/kg body weight) from ages 5 to 12 weeks. Systolic blood pressure (SBP) and heart rate (HR) were measured by indirect tail cuff method. During the analysis of the electrolytes and vasoactive hormones monitored in this study, it was found that rats fed high‐calcium diet had significantly elevated serum ionized and total calcium and calcium excretion. Systolic blood pressure for the verapamil‐normal calcium diet (week 5, 148 ± 4 mm Hg; week 7, 162 ± 4 mm Hg) did not differ significantly from that of normal calcium diet (week 5, 152 ± 2 mm Hg; week 7, 160 ± 1 mm Hg). The high‐calcium diet potentiated the development of hypertension, i.e, SBP was (157 ± 2 mm Hg) on the 5th week and (174 ± 4 mm Hg) on the 7th week. Conversely, verapamil high‐calcium diet prevented the development of hypertension (week 5, SBP was 139 ± 4 mm Hg; week 7, SBP was 146 ± 3 mm Hg). The authors conclude: (1) dietary calcium supplementation is prohypertensive in SHR; (2) dietary calcium must influence blood pressure in SHR by action at the verapamil calcium channel; (3) the antihypertensive efficacy of verapamil in SHR is not blocked by high‐calcium diet; (4) there may be a synergism between elevation of ionized serum calcium and verapamil with regard to antihypertensive effect of verapamil.