Jacobson H R, Furuya H, Breyer M D
Vanderbilt University Medical Center, Division of Nephrology, Nashville, Tennessee.
Kidney Int Suppl. 1991 Jul;33:S51-6.
Our understanding of transport and its regulation in the OMCDi has expanded significantly over the past 5 years. The OMCDi cells of the rabbit appear to be ideal for studying the mechanism and regulation of proton transport in a cell which is functionally similar to the alpha intercalated cell of the cortical collecting tubule. Characterization of the specific transporters at the apical and basolateral membrane allows us to explore further the mechanism whereby hormones and their second messengers regulate net transport in these cells. Simultaneous electrophysiologic measurements and determination of intracellular ion activities with fluorescent dyes, a technique we are currently employing in studies of single alpha and beta intercalated cells of the cortical collecting tubule, will be required to make progress in our study of regulation. Finally, characterization of the transporters has demonstrated that these cells are more complex than initially thought. Especially exciting is the possibility that the apical membrane proton extrusion step may be accomplished by more than one mechanism, i.e., a proton ATPase or an H(+)-K(+)-ATPase.
在过去5年里，我们对髓质集合管内段（OMCDi）的物质转运及其调节的理解有了显著扩展。兔的OMCDi细胞似乎是研究质子转运机制及其调节的理想模型，该细胞在功能上类似于皮质集合管的α闰细胞。对顶端膜和基底外侧膜上特定转运体的表征，使我们能够进一步探索激素及其第二信使调节这些细胞净转运的机制。若要在调节研究方面取得进展，就需要同时进行电生理测量，并使用荧光染料测定细胞内离子活性，我们目前正在皮质集合管单个α和β闰细胞的研究中采用这项技术。最后，对转运体的表征表明，这些细胞比最初认为的更为复杂。特别令人兴奋的是，顶端膜质子外排步骤可能由不止一种机制完成，即质子ATP酶或H(+)-K(+)-ATP酶。
