Bresler V M, Bresler S E, Nikiforov A A
Biochim Biophys Acta. 1975 Nov 3;406(4):526-37. doi: 10.1016/0005-2736(75)90030-9.
The active transport of organic anions through the plasma membrane of the proximal tubules of frog kidney was studied. For this purpose a marker anion, fluorescein, was used, its flow into the tubules registered by the increase of fluorescense. The kinetics of transport was measured as function of time, concentration of substrate, concentration of a competing acid (p-aminohippuric acid) and temperature. The process is inhibited by strophantin, a specific poison for (Na++K+)-dependent ATPase. These data show that fluorescein transport is effected with the participation of a charged carrier, probably by the downfield mechanism postulated by Mitchell. To confirm this mechanism, a passive flow of K+ was created inwards across the membrane of the proximal tubules by means of valinomycin. It led to the discharge of the membrane and to the inhibition of fluorescein transport. Anions are transported downfield across the membrane, probably in a state of complexes with two Na+ ions. A magnetic field of 10000-28000 oersted inhibits the fluorescein transport strongly. This can be regarded as a proof of the liquid-crystalline structure of biological membranes and demonstrates the importance of this structure for active transport.
对蛙肾近端小管质膜上有机阴离子的主动转运进行了研究。为此，使用了一种标记阴离子荧光素，通过荧光增强来记录其流入小管的情况。将转运动力学作为时间、底物浓度、竞争酸（对氨基马尿酸）浓度和温度的函数进行测定。该过程受到毒毛旋花子苷的抑制，毒毛旋花子苷是一种针对（Na++K+）依赖性ATP酶的特异性毒物。这些数据表明，荧光素的转运是在一种带电载体的参与下进行的，可能是通过米切尔提出的顺场机制。为了证实这一机制，通过缬氨霉素在近端小管膜内向内产生了K+的被动流动。这导致了膜的去极化并抑制了荧光素的转运。阴离子可能以与两个Na+离子形成复合物的状态顺场穿过膜。10000 - 28000奥斯特的磁场强烈抑制荧光素的转运。这可以被视为生物膜液晶结构的一个证据，并证明了这种结构对主动转运的重要性。
