Altura B M, Zhang A, Altura B T
Department of Physiology, State University of New York, Brooklyn 11203.
Miner Electrolyte Metab. 1993;19(4-5):323-36.
Abnormal dietary deficiency in Mg as well as abnormalities in Mg metabolism appear to play important roles as risk factors for ischemic heart disease and acute myocardial infarction, namely in hypertensive vascular disease, diabetic vascular disease, insulin resistance, atherosclerosis and vasospasm. Experimental, epidemiological as well as clinical evidence that supports a role for Mg in these risk factors are reviewed. Extracellular Mg ions ([Mg2+]o) exert important actions upon divalent cation metabolism, transport and intracellular release of [Ca2+]i and intracellular free Mg ([Mg2+]i) in both vascular smooth muscle and endothelial cells. Digital imaging microscopy, using molecular fluorescent probes, clearly indicates that both intracellular free Ca2+ and intracellular free Mg2+ are compartmented in both vascular smooth muscle cells and endothelial cells. [Mg2+]o appears to exert important effects on the precise subcellular location and concentration of both [Ca2+]i and [Mg2+]i. Use of specific ion-selective electrodes for [Mg2+]o has revealed that [Mg2+]o can change more rapidly than heretofore believed in cardiovascular pathophysiologic states. The latter new findings therefore suggest that the ionized level of [Mg2+]o is an important determinant of vascular tone, contractility and reactivity.
镁的异常饮食缺乏以及镁代谢异常似乎作为缺血性心脏病和急性心肌梗死的危险因素发挥重要作用，即在高血压性血管疾病、糖尿病性血管疾病、胰岛素抵抗、动脉粥样硬化和血管痉挛中。本文综述了支持镁在这些危险因素中发挥作用的实验、流行病学及临床证据。细胞外镁离子（[Mg2+]o）对血管平滑肌和内皮细胞中[Ca2+]i的二价阳离子代谢、转运及细胞内释放以及细胞内游离镁（[Mg2+]i）发挥重要作用。使用分子荧光探针的数字成像显微镜清楚地表明，细胞内游离Ca2+和细胞内游离Mg2+在血管平滑肌细胞和内皮细胞中均被分隔开来。[Mg2+]o似乎对[Ca2+]i和[Mg2+]i的精确亚细胞定位和浓度发挥重要影响。使用针对[Mg2+]o的特定离子选择性电极已揭示，在心血管病理生理状态下，[Mg2+]o的变化比以往认为的更快。因此，后一项新发现表明，[Mg2+]o的离子化水平是血管张力、收缩性和反应性的重要决定因素。
