Valberg P A
Science. 1984 May 4;224(4648):513-6. doi: 10.1126/science.6710153.
Sensitive magnetometry has shown that, after inhalation of airborne magnetic dust by humans or animals, particles retained within the lungs rotate. A number of mechanisms for this rotation have been proposed, including motions of breathing, particle thermal energy, cardiac pulsations, surface fluid flows, and macrophage cytoplasmic movements. In this study the cellular mechanism was examined by magnetometry and videomicroscopy of pulmonary macrophages removed from hamster lungs 1 day after inhalation of a maghemite (gamma-Fe2O3) aerosol. The field remaining after magnetization was measured in adherent cells and was found to decay rapidly to 30 percent of its initial magnitude within 12 minutes. The remanent-field decay rate was slowed by inhibitors of cytoplasmic motion. Videomicroscopy of pulmonary macrophages with phagocytized gamma-Fe2O3 showed amoeboid motions that rotated the particles away from their original direction of magnetization. The results confirm that macrophage cytoplasmic movement is a primary cause of remanent-field decay in lungs and that magnetometry can be used to quantify intracellular contractile activity.
灵敏的磁力测量法表明，人类或动物吸入空气中的磁性尘埃后，滞留在肺部的颗粒会发生旋转。人们已经提出了多种导致这种旋转的机制，包括呼吸运动、颗粒热能、心脏搏动、表面流体流动以及巨噬细胞胞质运动。在本研究中，通过对吸入磁赤铁矿（γ-Fe₂O₃）气溶胶1天后从仓鼠肺部取出的肺巨噬细胞进行磁力测量和视频显微镜观察，研究了细胞机制。测量了贴壁细胞磁化后剩余的磁场，发现其在12分钟内迅速衰减至初始强度的30%。细胞质运动抑制剂减缓了剩余磁场的衰减速率。对吞噬了γ-Fe₂O₃的肺巨噬细胞进行视频显微镜观察，发现其呈现出变形虫样运动，使颗粒偏离其原始磁化方向。结果证实，巨噬细胞胞质运动是肺部剩余磁场衰减的主要原因，并且磁力测量法可用于量化细胞内收缩活动。
