0.4 mT工频磁场对骨骼肌肌质网囊泡游离钙离子转运的影响

目的探讨工频磁场对骨骼肌肌质网钙转运动力学的影响.方法利用动态光谱法检测0.4 mT、50 Hz正弦磁场辐照过的骨骼肌肌质网Ca2+转运和钙泵活性,用3H-兰尼碱结合实验检测Ca2+释放通道的活性,用荧光偏振法检测肌质网膜的流动性等.结果 0.4 mT、50 Hz正弦磁场辐照导致提取的肌质网囊泡Ca2+摄取初速率由每秒(29.18±3.90) pmol/mg下降到(24.60±3.81) pmol/mg,钙泵的活性由每分钟(0.93±0.05) μmol/mg下降到(0.69±0.07) μmol/mg;导致Ca2+释放初速率由每秒(4.83±0.82) pmol/mg上升到(5.65±0.43) pmol/mg,3H-兰尼碱结合度由(1.10±0.12) pmol/mg上升到(1.16±0.13) pmol/mg,分别上升了15%和5%.结论 0.4 mT工频磁场辐照引起的肌质网Ca2+摄取下调和Ca2+释放上调是由于肌质网钙泵活性降低和Ca2+释放通道活性升高所致.

Effects of power frequency magnetic field on Ca2+ transport of skeletal muscle sarcoplasmic reticulum vesicles

OBJECTIVE: To investigate the effects of power frequency magnetic field on the Ca2+ transport dynamics of isolated sarcoplasmic reticulum vesicles. METHODS: The assays of Ca2+ uptake time course and the Ca2+-ATPase activity of sarcoplasmic reticulum vesicles were investigated by using dynamic mode of spectrometry with a Ca2+ dye; Ca2+ release channel activation was examined by 3H-ryanodine binding and Ca2+ release assays; membrane fluidity of sarcoplasmic reticulum vesicles was examined by fluorescence polarization, without or with exposure to the vesicles at a 0.4 mT, 50 Hz sinusoidal magnetic field. RESULTS: 0.4 mT, 50 Hz sinusoidal magnetic field exposure caused about a 16% decline of the initial Ca2+ uptake rate from a (29.18 +/- 3.90) pmol.mg(-1).s(-1) to a (24.60 +/- 3.81) pmol.mg(-1).s(-1) and a 26% decline of the Ca2+-ATPase activity from (0.93 +/- 0.05) micromol.mg(-1).min(-1) to (0.69 +/- 0.07) micromol.mg(-1).min(-1) of sarcoplasmic reticulum vesicles, whereas caused a 15% increase of the initial Ca2+ release rate from (4.83 +/- 0.82) pmol.mg(-1).s(-1) to (5.65 +/- 0.43) pmol.mg(-1).s(-1) and a 5% increase in 3H-ryanodine binding to the receptor from (1.10 +/- 0.12) pmol/mg to (1.16 +/- 0.13) pmol/mg, respectively. CONCLUSION: The decline of Ca2+-ATPase activity and the increase of Ca2+ release channel activity should result in a down-regulation of Ca2+ dynamic uptake and an up-regulation of Ca2+ release induced by exposing the sarcoplasmic reticulum to a 0.4 mT, 50 Hz power frequency magnetic field.