Effects of exposure to a time-varying 1.5 T magnetic field on the neurotransmitter-activated increase in intracellular Ca²⁺ in relation to actin fiber and mitochondrial functions in bovine adrenal chromaffin cells

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• 作者：Toshitaka Ikehara ; Hirotaka Nishisako ; Yuki Minami ; Hiromi Ichinose(Sasaki) ; Tairo Shiraishi ; Mitsuo Kitamura ; Masayuki Shono ; Hitoshi Houchi ; Kazuyoshi Kawazoe ; Kazuo Minakuchi ; Kazuo Yoshizaki ; Yohs
• 关键词：Electromagnetic field ; Ca²⁺ release ; F-actin ; mitochondria ; endoplasmic reticulum ; Eddy currents
• 刊名：Biochimica et Biophysica Acta (BBA)/General Subjects
• 出版年：2010
• 出版时间：December 2010
• 年：2010
• 卷：1800
• 期：12
• 页码：1221-1230
• 全文大小：1855 K

文摘

Background

It has been reported that exposure to electromagnetic fields influences intracellular signal transduction. We studied the effects of exposure to a time-varying 1.5 T magnetic field on membrane properties, membrane cation transport and intracellular Ca²⁺ mobilization in relation to signals. We also studied the mechanism of the effect of exposure to the magnetic field on intracellular Ca²⁺ release from Ca²⁺ stores in adrenal chromaffin cells.

Methods

We measured the physiological functions of ER, actin protein, and mitochondria with respect to a neurotransmitter-induced increase in Ca²⁺ in chromaffin cells exposed to the time-varying 1.5 T magnetic field for 2 h.

Results

Exposure to the magnetic field significantly reduced the increase in [Ca²⁺]i. The exposure depolarized the mitochondria membrane and lowered oxygen uptake, but did not reduce the intracellular ATP content. Magnetic field-exposure caused a morphological change in intracellular F-actin. F-actin in exposed cells seemed to be less dense than in control cells, but the decrease was smaller than that in cytochalasin D-treated cells. The increase in G-actin (i.e., the decrease in F-actin) due to exposure was recovered by jasplakinolide, but inhibition of Ca²⁺ release by the exposure was unaffected.

Conclusions and general significance

These results suggest that the magnetic field-exposure influenced both the ER and mitochondria, but the inhibition of Ca²⁺ release from ER was not due to mitochondria inhibition. The effect of eddy currents induced in the culture medium may indirectly influence intracellular actin and suppress the transient increase in [Ca²⁺]i.