Mechanisms of the antihypertensive effects of dietary calcium and role of calcitonin gene related peptide in hypertension.
Alterations in calcium metabolism and calcium-regulating hormones have been described in essential hypertension. However, the mechanisms that mediate these responses are unknown. In previous studies, using the genetically spontaneously hypertensive rat and the mineralocorticoid-salt (DOC-salt) hypertensive rat model, we and others have observed that oral calcium supplementation attenuates the associated increase in peripheral vascular resistance and consequently lowers blood pressure (BP). When hypertensive patients (n = 8, diastolic BP 90-95 mmHg (1 mmHg = 133.3 Pa)) were given daily oral calcium supplementation (1.4 g elemental calcium), both systolic and diastolic BP were decreased (5-10 mmHg, p < 0.01). The only biochemical variables significantly changed were serum ionized calcium and intact parathyroid hormone (PTH, 1-84) (p < 0.05); furthermore, the levels of calcitonin gene related peptide (CGRP), measured by both radioimmunoassay and radioreceptor assay, showed a marked 75% increase (p < 0.001). The antihypertensive effects of Ca2+ and the increased levels of CGRP in the circulation returned to baseline levels immediately following cessation of calcium supplementation, suggesting that the effects of calcium on BP and CGRP are specific. On the basis of these observations were proposed that the antihypertensive effect of dietary calcium supplementation, at least in part, is mediated through CGRP.
Wimalawansa
S J
SJ
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-1065, USA.
Supowit
S C
SC
DiPette
D J
DJ
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D015740:Calcitonin Gene-Related Peptide / Q000097:blood / Q000502:physiology*; D002136:Calcium, Dietary / Q000494:pharmacology*; D003900:Desoxycorticosterone; D006801:Humans; D006973:Hypertension / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D051381:Rats
D000959:Antihypertensive Agents; D002136:Calcium, Dietary; D003900:Desoxycorticosterone; D015740:Calcitonin Gene-Related Peptide