Central neural mechanism contributing to attenuation of angiotensin II-induced hypertension in rats on dietary calcium supplementation.
The effect of dietary calcium (Ca) supplementation on blood pressure (BP) and the central nervous system (CNS) mechanism underlying this effect were studied in angiotensin II (Ang II)-induced hypertensive rats. The effects of dietary Ca (0.5, 2, 4%) on systolic blood pressure (SBP), ionized Ca concentration (Ca++) in cerebrospinal fluid (CSF) and central norepinephrine (NE) turnover were investigated in male Wistar rats receiving subcutaneous infusion of Ang II (100 ng/min). Central NE turnover was studied by measuring 3-methoxy-4-hydroxyphenylglycol (MHPG) concentration in CSF with multiple electrode liquid chromatography. Ang II significantly increased SBP, and dietary Ca dose-dependently attenuated the increase. SBP inversely correlated with Ca++ and MHPG in CSF. Intracerebroventricular injection of CaCl2 more markedly reduced BP in Ang II-treated rats than that in control rats. These results suggest that modulation of central NE turnover possibly caused by the increase in CNS Ca++ is involved in the anti-hypertensive mechanism of dietary Ca supplementation in Ang II-induced hypertensive rats.
Kim
S
S
Department of Geriatrics, Faculty of Medicine, University of Tokyo, Japan.
Ouchi
Y
Y
Iijima
S
S
Toba
K
K
Orimo
H
H
D000804:Angiotensin II / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000097:blood / Q000134:cerebrospinal fluid; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002490:Central Nervous System / Q000187:drug effects / Q000503:physiopathology*; D004231:Diuresis / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000134:cerebrospinal fluid; D009318:Natriuresis / Q000187:drug effects; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002136:Calcium, Dietary; D000804:Angiotensin II; D008734:Methoxyhydroxyphenylglycol; D002118:Calcium; D009638:Norepinephrine