Gerencser G A
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
Am J Physiol. 1988 Jan;254(1 Pt 2):R127-33. doi: 10.1152/ajpregu.1988.254.1.R127.
A Cl--stimulated adenosinetriphosphatase (ATPase) activity and an ATP-dependent Cl- transport process were found in Aplysia enterocyte plasma membranes. In an attempt to further elucidate this transport process plasma membrane vesicles from Aplysia enterocytes were prepared utilizing differential centrifugation and sucrose density gradient techniques. Electrogenicity of the ATP-dependent Cl- transport was confirmed in three ways. First, an inwardly directed valinomycin-induced K+ diffusion potential, making the vesicle interior electrically positive, enhanced ATP-driven Cl- uptake compared with vesicles lacking the ionophore. Second, ATP plus Cl- increased intravesicular negativity measured by lipophilic triphenylmethylphosphonium distribution across the vesicular membrane. Third, both vanadate and thiocyanate inhibited the ATP plus Cl--dependent intravesicular negativity. These results are consistent with the hypothesis that the active electrogenic Cl- transport mechanism in Aplysia intestine could be a Cl--stimulated ATPase found in the enterocyte plasma membrane.
在海兔肠上皮细胞质膜中发现了一种氯离子刺激的三磷酸腺苷酶（ATP酶）活性以及一个依赖ATP的氯离子转运过程。为了进一步阐明这种转运过程，利用差速离心和蔗糖密度梯度技术制备了来自海兔肠上皮细胞的质膜囊泡。通过三种方式证实了依赖ATP的氯离子转运的电生性。第一，内向的缬氨霉素诱导的钾离子扩散电位使囊泡内部呈电正性，与缺乏离子载体的囊泡相比，增强了ATP驱动的氯离子摄取。第二，ATP加氯离子增加了通过亲脂性三苯基甲基鏻在囊泡膜上的分布所测量的囊泡内负性。第三，钒酸盐和硫氰酸盐都抑制了ATP加氯离子依赖的囊泡内负性。这些结果与以下假设一致，即海兔肠道中活跃的电生性氯离子转运机制可能是在肠上皮细胞质膜中发现的一种氯离子刺激的ATP酶。
