Waldeck A R, Kuchel P W
Department of Biochemistry, University of Sydney, New South Wales, Australia.
Biophys J. 1993 May;64(5):1445-55. doi: 10.1016/S0006-3495(93)81511-X.
A model system to observe and investigate the transfer of Na+ ions between different internal compartments in suspension of liposomes was developed, and the exchange was followed by nuclear magnetic resonance spectroscopy. The experiments were performed under conditions of a Donnan equilibrium. Quantitative analysis of this three-site transmembrane exchange system allowed us to distinguish between direct and indirect exchange between liposomes. It also disclosed a "confining" effect on the exchange between the two populations of liposomes. This confining effect may have been due to an electrostatic field in the presence of a membrane potential. Donnan potentials and ionic compositions at equilibrium for the three-compartment system were calculated numerically. The model system may be used to explore further the effects of membrane potentials, surface potentials, and ionic mobilities on ion transport in biological (model) systems in general.
开发了一个用于观察和研究脂质体悬浮液中不同内部隔室之间Na⁺离子转移的模型系统，并通过核磁共振光谱对交换过程进行跟踪。实验在唐南平衡条件下进行。对这个三位点跨膜交换系统的定量分析使我们能够区分脂质体之间的直接交换和间接交换。它还揭示了对两类脂质体之间交换的“限制”作用。这种限制作用可能是由于存在膜电位时的静电场所致。对三室系统平衡时的唐南电位和离子组成进行了数值计算。该模型系统一般可用于进一步探索膜电位、表面电位和离子迁移率对生物（模型）系统中离子运输的影响。
