Barbier E, Dufy B, Veyret B
Laboratoire de Physique des Interactions Ondes-Matière, C.N.R.S., E.N.S.C.P.B., Université Bordeaux I, Talence, France.
Bioelectromagnetics. 1996;17(4):303-11. doi: 10.1002/(SICI)1521-186X(1996)17:4<303::AID-BEM6>3.0.CO;2-7.
The effect of exposure of single rat pituitary cells to 50 Hz sine wave magnetic fields of various strengths on the intracellular free Ca2+ concentration ([Ca2+]i), was studied by using dual-emission microfluorimetry, using indo-1 as probe. A 30 min exposure of the cells to vertical 50 microT peak magnetic field triggered a long-lasting increase in [Ca2+]i from a basal value of about 185 +/- 4 nM to 326 +/- 41 nM (S.E.; n = 150). The vertical and horizontal components of the static magnetic field were 57 and 15 microT, respectively. The 50 Hz ambient magnetic field was always below 0.1 microT rms. The effect was observed both at 25 +/- 2 degrees C and at 37 +/- 2 degrees C. Responsive cells, for which [Ca2+]i rose to values above 309 nM, were identified as lactotrophs and represented 29% of the total pituitaries. [Ca2+]i increase, for the most part, was due to Ca2+ influx through voltage-dependent dihydropiridine-sensitive calcium channels inhibited by PN 200-110. However, neither Ca2+ channel blockers nor removal of Ca2+ from the external medium during exposure completely prevented the field-induced [Ca2+]i increase. Additional experiments using an MTT colorimetric assay showed that alteration of Ca2+ homeostasis of lactotrophs was associated with impairment of some mitochondrial processes.
利用双发射显微荧光测定法，以indo-1为探针，研究了不同强度的50Hz正弦波磁场对单个大鼠垂体细胞细胞内游离Ca2+浓度（[Ca2+]i）的影响。将细胞垂直暴露于50μT峰值磁场30分钟，可使[Ca2+]i从约185±4 nM的基础值持续增加至326±41 nM（标准误；n = 150）。静磁场的垂直和水平分量分别为57μT和15μT。50Hz的环境磁场均方根值始终低于0.1μT。在25±2℃和37±2℃时均观察到该效应。[Ca2+]i升高至309 nM以上的反应性细胞被鉴定为催乳素细胞，占垂体总数的29%。[Ca2+]i的增加大部分是由于Ca2+通过电压依赖性二氢吡啶敏感钙通道内流，该通道受PN 200 - 110抑制。然而，在暴露期间，无论是Ca2+通道阻滞剂还是从外部培养基中去除Ca2+，都不能完全阻止磁场诱导的[Ca2+]i增加。使用MTT比色法进行的额外实验表明，催乳素细胞Ca2+稳态的改变与某些线粒体过程的损害有关。
