Stahlhofen W, Möller W
GSF-Forschungszentrum für Umwelt und Gesundheit, Institut für Biophysikalische Strahlenforschung, Frankfurt am Main, Germany.
Toxicol Lett. 1994 Jun;72(1-3):127-36. doi: 10.1016/0378-4274(94)90019-1.
Magnetic microparticles were used to investigate the defence system of the human lungs against foreign material. About 0.5 mg of spherical monodisperse magnetite particles were deposited in the alveolar region of the human lung by voluntary inhalation. After primary magnetization a remanent magnetic field (RMF) of the lung can be measured that allows estimation of the amount of dust retained in the lung. The decay of this RMF, called relaxation, results from a misalignment of the dipole particles due to the activity of pulmonary macrophages. This macrophage activity was characterized by a cell energy Ez. With a secondary magnetization the lung can be remagnetized by rotation of the dipole particles. This allows estimation of the intracellular viscosity and the motility of the alveolar macrophages in vivo. The macrophage cell-line J774 was used to verify the dynamic processes of the magnetic particles within the cells in vitro. In vitro and in vivo relaxation curves of polydisperse and of spherical monodisperse magnetite particles are presented. Thermal relaxation of mono-disperse and polydisperse particles within a viscous standard could be verified with the Brownian rotary diffusion model. Relaxation with monodisperse particles was double exponential in vivo as well as in vitro, suggesting that 2 different viscous compartments of the cytoplasm should be considered. Relaxation in the macrophage cell-line J774 was particle-size-dependent.
磁性微粒被用于研究人类肺部对外来物质的防御系统。通过自愿吸入，将约0.5毫克球形单分散磁铁矿颗粒沉积在人类肺部的肺泡区域。初次磁化后，可以测量肺部的剩余磁场（RMF），从而估算肺部留存的灰尘量。这种RMF的衰减，即弛豫，是由于肺巨噬细胞的活动导致偶极子颗粒排列紊乱所致。这种巨噬细胞活性以细胞能量Ez为特征。通过二次磁化，可以通过偶极子颗粒的旋转使肺部重新磁化。这可以在体内估算细胞内粘度和肺泡巨噬细胞的运动性。巨噬细胞系J774被用于在体外验证细胞内磁性颗粒的动态过程。给出了多分散和球形单分散磁铁矿颗粒的体外和体内弛豫曲线。利用布朗旋转扩散模型可以验证粘性标准液中单分散和多分散颗粒的热弛豫。单分散颗粒的弛豫在体内和体外均为双指数形式，这表明应考虑细胞质的2个不同粘性区室。巨噬细胞系J774中的弛豫与颗粒大小有关。
