FLASH-PHOTOLYSIS OF MAGNESIUM-DM-NITROPHEN IN HEART-CELLS - A NOVEL-APPROACH TO PROBE MAGNESIUM-DEPENDENT AND ATP-DEPENDENT REGULATION OF CALCIUM CHANNELS

被引：11

作者：

BACKX, PH

OROURKE, B

MARBAN, E

机构：

[1] Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD

来源：

AMERICAN JOURNAL OF HYPERTENSION | 1991年 / 4卷 / 07期

关键词：

MAGNESIUM; CALCIUM; VENTRICULAR MYOCYTES; FLASH PHOTOLYSIS;

D O I：

10.1093/ajh/4.7.416S

中图分类号：

R6 [外科学];

学科分类号：

1002 ; 100210 ;

摘要：

Changes in cytoplasmic magnesium concentration in the millimolar range are known to evoke directionally opposite changes in the amplitude of cardiac L-type calcium current, but the effects of magnesium changes in the micromolar range are not known. This concentration range is particularly interesting for two reasons: open-channel block of some ion channels (eg, the inward rectifier) occurs with a micromolar K(d); and magnesium at such low levels may limit the availability of magnesium adenosine triphosphate (MgATP) and magnesium guanidine triphosphate (MgGTP) for a variety of enzymatic processes, including calcium channel phosphorylation. To investigate the effects of critical magnesium depletion and its sudden reversal, we used flash photolysis to liberate magnesium from intracellular DM-nitrophen in guinea pig heart cells. Under our conditions, intracellular [Mg2+] changed from 0.25-mu-mol/L before the flash to less-than-or-equal-to 200-mu-mol/L afterwards. Calcium channel currents carried by either calcium or barium consistently increased after flash, a directional change opposite to the reported effects of elevated [Mg2+] in the millimolar range. Our data do not yet enable us to understand the basis of the magnesium effect, but we are particularly interested in the possibility that the sudden appearance of magnesium enables calcium channel phosphorylation.

引用

页码：S416 / S421

页数：6

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