Relationship between total and free cellular Mg2+ during metabolic stimulation of rat cardiac myocytes and perfused hearts
Relationship between total and free cellular Mg2+ during metabolic stimulation of rat cardiac myocytes and perfused hearts
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DOI：
10.1006/abbi.1999.1619
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发表时间：
2000-02-15
影响因子：
3.9
通讯作者：
Scarpa, A
中科院分区：
文献类型：
--
作者：
Fatholahi, M;LaNoue, K;Scarpa, A
将总镁的变化与胶原酶分散的大鼠心肌细胞或朗宁多夫灌流的大鼠心脏在代谢刺激过程中胞内游离镁的变化进行比较。在心肌细胞中，加入导致cAMP增加或蛋白激酶C激活的药物会导致在3分钟内总镁含量的损失或增加超过5%(即3-4nmol mg/mg蛋白)。在相同条件下，用荧光指示剂测定的细胞内游离镁离子的变化很小，导致细胞内游离镁离子的变化相当于90-140mU M。在灌流的心脏中，β-肾上腺素能刺激导致每克心脏的总镁损失大于0.5mU/g，相当于心脏总镁含量的9%损失(估计为5.8mU/g)。在此条件下，细胞内游离镁离子或细胞内镁离子的主要缓冲液ATP没有变化，如P-31核磁共振所测。这些数据表明，在观察到的细胞内总镁的大量转运过程中，为了保持胞内游离镁的相对不变，细胞内总镁发生了较大的重新分配。因此，镁离子可能不是在胞浆内调节代谢功能，而是在其浓度波动的位置，如胞外液和胞内室。(C)2000年学术出版社。
The changes in total Mg were compared with changes in cytosolic free Mg2+ during metabolic stimulation of collagenase-dispersed rat cardiac myocytes or Langendorff-perfused rat hearts. In myocytes the addition of agents leading to cAMP increase or protein kinase C activation results in a loss or gain of more than 5% of total Mg content within 3 min (i.e., 3-4 nmol Mg/mg protein). Under the same conditions, changes in cytosolic free Mg2+ measured with fluorescent indicator are small and result in changes of cytosolic free Mg2+ equivalent to 90-140 mu M. In perfused hearts, beta-adrenergic stimulation results in a loss of total Mg larger than 0.5 mu mol per gram of heart corresponding to 9% loss of total Mg content of the heart (estimated to be 5.8 mu mol). Under these conditions there is no change in cytosolic free Mg2+ Or the major buffer of cytosolic Mg2+, ATP, as measured by P-31 NMR. These data suggest that a major redistribution of total Mg occurs in intracellular organelles or in cytosolic buffers in order to maintain cytosolic free Mg2+ relatively unchanged during the observed cellular massive translocation of total Mg. Hence, Mg2+ may regulate metabolic functions not within the cytosol but in locations where its concentration oscillates, such as extracellular fluid and intracellular compartments. (C) 2000 Academic Press.