The effect of high calcium intake on intracellular free [Ca2+] and Na(+)-H+ exchange in DOC-NaCl-hypertensive rats

Aldosteronism and a Proinflammatory Vascular Phenotype

Background— Chronic, inappropriate (relative to dietary Na + ) elevations in circulating aldosterone, such as occur in congestive heart failure, are accompanied by a proinflammatory vascular phenotype involving the coronary and systemic vasculature. An immunostimulatory state with activated peripheral blood mononuclear cells (PBMCs) precedes this phenotype and is induced by a fall in cytosolic free [Mg 2+ ] i and subsequent Ca 2+ loading of these cells and transduced by oxidative/nitrosative stress.

Methods and Results— We sought to further validate this hypothesis in rats with aldosterone/1%NaCl treatment (ALDOST) by using several interventions as cotreatment: a Mg 2+ -supplemented diet; amlodipine, a CCB; and N -acetylcysteine, an antioxidant. Blood samples were obtained at weeks 1 to 4 of ALDOST to monitor [Mg 2+ ] i , [Ca 2+ ] I , and H 2 O 2 production in PBMCs. Coronal ventricular sections were examined for invading inflammatory cells and 3-nitrotyrosine labeling, a marker of oxidative/nitrosative stress. In response to ALDOST and compared with untreated controls, we found an early and persistent reduction in [Mg 2+ ] i with a subsequent rise in [Ca 2+ ] i and H 2 O 2 production, each of which was either attenuated or abrogated by the Mg 2+ -supplemented diet and by N -acetylcysteine, whereas amlodipine prevented Ca 2+ loading and an altered redox state. Cotreatment with these interventions either markedly attenuated or prevented the appearance of the proinflammatory coronary vascular phenotype and the presence of 3-nitrotyrosine in invading inflammatory cells.

Conclusions— We suggest that the immunostimulatory state that appears during aldosteronism and leads to a proinflammatory coronary vascular phenotype is induced by a fall in [Mg 2+ ] i with Ca 2+ loading of PBMCs and is transduced by H 2 O 2 production in these cells.