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Effects of magnesium on prostacyclin synthesis and intracellular free calcium concentration in vascular cells
Magnesium Research. Volume 17, Number 1, 20-7, March 2004, ORIGINAL ARTICLE
Free Article
Author(s) : Kazuo Satake, Jong‐Dae Lee, Hiromasa Shimizu, Hiroyasu Uzui, Yasuhiko Mitsuke, Hong Yue, Takanori Ueda
Summary : This study investigated the effects of extracellular magnesium concentration ([Mg ²⁺ _]e\; 0.3‐3 mM) on intracellular free calcium concentration ([Ca ²⁺ _]i) and prostacyclin (PGI ₂) production in cultured human umbilical vein endothelial cells (HUVEC) and vascular smooth muscle cells from rats (VSMC) under basal and agonist‐stimulated conditions. We used histamine as agonist which increases [Ca ²⁺ _]i and PGI ₂ production in HUVEC, norepinephrine in VSMC. [Mg ²⁺ _]e dose‐dependently increased basal and agonist‐stimulated PGI ₂ production in both cells. [Mg ²⁺ _]e dose‐dependently reduced basal [Ca ²⁺ _]i in VSMC, but did not influence in HUVEC. In both cells, increasing [Mg ²⁺ _]e reduced agonist‐stimulated [Ca ²⁺ _]i responses. Furthermore, [Mg ²⁺ _]e dose‐dependently reduced agonist‐stimulated [Ca ²⁺ _]i in Ca ²⁺ ‐free buffer, indicating intracellular Ca ²⁺ release. In VSMC, 10 ^‐‐6 M diltiazem and 10 ^‐7 M nifedipine, Ca ²⁺ channel blockers, reduced agonist‐stimulated [Ca ²⁺ _]i as well as 3 mM Mg ²⁺, but did not affect PGI ₂ production. [Mg ²⁺ _]e amplified dose‐dependently arachidonic acid‐induced PGI ₂ production in both cells, suggesting the activation of cyclooxygenase and\\or PGI ₂ synthetase. Our results suggest that [Mg ²⁺ _]e influences intracellular Ca ²⁺ mobilization of not only vascular smooth muscle cells but also endothelial cells by inhibiting both Ca ²⁺ influx and intracellular Ca ²⁺ release. [Mg ²⁺ _]e enhances PGI ² production in both types of cells, although the mechanism is likely to be independent from Ca ²⁺ mobilization.
Keywords : magnesium, vascular endothelial cells, vascular smooth muscle cells, intracellular free calcium concentration, prostacyclin

Effects of magnesium on prostacyclin synthesis and intracellular free calcium concentration in vascular cells