Viscio D B, Prestegard J H
Proc Natl Acad Sci U S A. 1981 Mar;78(3):1638-42. doi: 10.1073/pnas.78.3.1638.
Nuclear magnetic resonance techniques developed to study membrane permeability in closed membrane systems have been used to investigate transport of 5-hydroxytryptamine across the phospholipid membranes of large unilamellar vesicles. The vesicles, modeling the 5-hydroxytryptamine storage organelles of blood platelets, contained a high internal level of ATP buffered at a pH low relative to the external solution. The resultant pH gradient drove accumulation of 5-hydroxytryptamine to a level consistent with selective transport of the neutral amine. The upfield shifts of the 5-hydroxytryptamine resonances resulting from complexation with internally confined ATP were utilized to resolve and, simultaneously, to observe the internal and external amine. Simulation of the time evolution of the 5-hydroxytryptamine concentration allowed measurement of a permeability coefficient of 1.4 +/- 0.5 X 10(-5) cm/sec for the neutral amine.
为研究封闭膜系统中的膜通透性而开发的核磁共振技术，已被用于研究5-羟色胺跨大单层囊泡磷脂膜的转运。这些囊泡模拟血小板的5-羟色胺储存细胞器，内部含有相对于外部溶液pH值较低时缓冲的高浓度ATP。由此产生的pH梯度驱使5-羟色胺积累到与中性胺选择性转运一致的水平。利用与内部受限ATP络合导致的5-羟色胺共振的高场位移来分辨并同时观察内部和外部胺。对5-羟色胺浓度随时间变化的模拟使得能够测量中性胺的渗透系数为1.4±0.5×10^(-5) cm/秒。
