TY - JOUR
T1 - Effects of calcium and deoxycorticosterone on blood pressure, plasma renin activity and vascular reactivity in spontaneously hypertensive rats
AU - Pörsti, I
AU - Wuorela, H
AU - Arvola, P
AU - Säynävälammi, P
AU - Nurmi, A K
AU - Huhtala, H
AU - Laippala, P
AU - Metsä-Ketelä, T
AU - Vapaatalo, H
PY - 1990
Y1 - 1990
N2 - The effects of calcium and deoxycorticosterone (DOC) on blood pressure, plasma renin activity (PRA), urinary sodium excretion and aortic responses were studied in spontaneously hypertensive rats (SHR). The animals (age 9 weeks) were divided into four treatment groups: control, calcium, DOC and DOC+calcium (n = 12 and the mean systolic blood pressure 174-177 mmHg in each). Calcium was given as 1.5% CaCl2 in drinking fluid, and DOC trimethylacetate by weekly injections (25 mg/kg s.c.). During the 4-week study systolic blood pressure rose in all groups, but the increase was attenuated by calcium (final levels: control 201 +/- 3, calcium 186 +/- 3, DOC 206 +/- 2, DOC + calcium 203 +/- 2 mmHg, mean +/- SE). PRA was reduced in both groups receiving DOC, but it was not affected by calcium. Calcium supplementation increased urinary excretion of sodium in DOC-treated animals. DOC enhanced the in vitro contractility of helically cut aortic strips to noradrenaline, and decreased the relaxation of the strips to nitroprusside and nifedipine. The results indicate that calcium supplementation attenuates the development of hypertension in SHR, and that this attenuation is not mediated by the renin-angiotensin system. DOC abolished this lowering effect of calcium on blood pressure possibly by its action on vascular smooth muscle, resulting in increased vascular contractility and impaired relaxation.
AB - The effects of calcium and deoxycorticosterone (DOC) on blood pressure, plasma renin activity (PRA), urinary sodium excretion and aortic responses were studied in spontaneously hypertensive rats (SHR). The animals (age 9 weeks) were divided into four treatment groups: control, calcium, DOC and DOC+calcium (n = 12 and the mean systolic blood pressure 174-177 mmHg in each). Calcium was given as 1.5% CaCl2 in drinking fluid, and DOC trimethylacetate by weekly injections (25 mg/kg s.c.). During the 4-week study systolic blood pressure rose in all groups, but the increase was attenuated by calcium (final levels: control 201 +/- 3, calcium 186 +/- 3, DOC 206 +/- 2, DOC + calcium 203 +/- 2 mmHg, mean +/- SE). PRA was reduced in both groups receiving DOC, but it was not affected by calcium. Calcium supplementation increased urinary excretion of sodium in DOC-treated animals. DOC enhanced the in vitro contractility of helically cut aortic strips to noradrenaline, and decreased the relaxation of the strips to nitroprusside and nifedipine. The results indicate that calcium supplementation attenuates the development of hypertension in SHR, and that this attenuation is not mediated by the renin-angiotensin system. DOC abolished this lowering effect of calcium on blood pressure possibly by its action on vascular smooth muscle, resulting in increased vascular contractility and impaired relaxation.
KW - Animals
KW - Blood Pressure/drug effects
KW - Blood Vessels/drug effects
KW - Body Weight/drug effects
KW - Calcium/pharmacology
KW - Desoxycorticosterone/pharmacology
KW - Diuresis/drug effects
KW - Dose-Response Relationship, Drug
KW - Male
KW - Nifedipine/pharmacology
KW - Nitroprusside/pharmacology
KW - Norepinephrine/pharmacology
KW - Rats
KW - Rats, Inbred SHR
KW - Renin/blood
KW - Sodium/urine
KW - Vasoconstriction/drug effects
U2 - 10.3109/10641969009074746
DO - 10.3109/10641969009074746
M3 - Article
C2 - 2257685
VL - 12
SP - 1159
EP - 1174
IS - 7
ER -