title: Dietary calcium reduces blood pressure, parathyroid hormone, and platelet cytosolic calcium responses in spontaneously hypertensive rats.
abstract: Dietary calcium effects on blood pressure, parathyroid hormone (PTH), and platelet cytosolic calcium concentrations were investigated. The dietary calcium (low, 0.2%; medium, 0.5%; and high, 2.0% wt/wt) was supplemented in spontaneously hypertensive rats from 6 through 22 weeks of age. Mean systolic blood pressure was decreased by age 12 weeks with calcium supplementation (low, 227 +/- 6 mm Hg; medium, 211 +/- 6 mm Hg; and high, 182 +/- 7 mm Hg; P < .001). By the 10th week of age, the low calcium group had significantly (P < .05) more elevated (44 +/- 2.3 pg/ml) plasma PTH compared with the high calcium-supplemented group (15 +/- 4.5 pg/mL). Regression analysis showed a significant (P < .001) positive correlation (r = 0.3) between systolic blood pressure and PTH. The platelet cytosolic calcium concentration was determined using the fura-2 method. The basal calcium was 134 +/- 5.5 nmol/L for the low calcium group and thrombin increased to 228 +/- 8 nmol/L (P < .0001; +70% change). The normal calcium group had 202 +/- 8 nmol/L; thrombin increased to 239 +/- 10 nmol/L (P < .0026; +19% change). The high calcium group had basal levels 145 +/- 7 nmol/L, with thrombin stimulating to 212 +/- 8 nmol/L (P < .0001; +46% change). Although thrombin increased platelet cytosolic calcium concentration in all groups, normal and high dietary calcium groups had smaller percentage increases (51% and 24% lesser, respectively) compared with the low dietary calcium group.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Calcium Hypertension Research Lab, Charles R. Drew University of Medicine and Science, Los Angeles, California 90059.
authors.forename: R M
authors.initials: RM
authors.lastname: Rao
authors.forename: Y
authors.initials: Y
authors.lastname: Yan
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000097:blood*; D002136:Calcium, Dietary / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D006973:Hypertension / Q000097:blood* / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D051381:Rats; D011918:Rats, Inbred SHR
chemical_list: D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D002118:Calcium