VIEWING THE KIDNEY THROUGH MICROELECTRODES
VIEWING THE KIDNEY THROUGH MICROELECTRODES
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DOI：
10.1152/ajprenal.1984.247.5.f695
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发表时间：
1984-01-01
影响因子：
--
通讯作者：
FROMTER, E
中科院分区：
文献类型：
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作者：
FROMTER, E
微电极电学测量在研究肾离子转运机制方面具有重要价值。凭借其细小的尖端(直径小于1微米)以及易于记录电瞬变，它们提供了无与伦比的空间和时间分辨率的测量。早期的电生理工作主要是在两栖动物身上进行的，因为它们的细胞尺寸较大，而对哺乳动物的研究仅限于跨上皮电参数，这对个别膜机制没有提供深入的了解。然而，最近已经开发出了在体内和体外成功地穿透哺乳动物肾脏的单个肾小管细胞的技术。这样的实验使我们能够通过电势对管腔和/或管周流体成分的快速扰动或对外加电流的响应来识别单个细胞膜的离子传输特性。离子选择性微电极的发展大大提高了这种方法的能力，使我们能够直接测量细胞内Na+、K+、Cl-、Ca~(2+)和HCO3-的浓度或pH，并定量跟踪它们对不同实验操作的变化。本文综述了我们对哺乳动物近端肾小管上皮细胞膜离子转运机制的认识，重点介绍了Na+、K+、HCO3-和Cl-的转运。除了氯离子在数量上不那么重要的跨细胞转运外，所有其他离子的主要转运机制都已在刷状缘和管周细胞膜中被确定。重点描述了HCO3-穿过肾小管周围细胞膜的情况，迄今为止，除了电生理技术外，还没有人对其进行过研究。微电极技术可能会继续提供新的洞察力，当在细胞水平上研究调控现象，并利用新开发的膜片钳技术识别肾细胞膜上的单个电导通道时。
Electrical measurements with microelectrodes have proven of great value in the investigation of renal ion transport mechanisms. By virtue of their fine tips (less than 1 micron in diameter) and because of the ease of recording electrical transients, they provide measurements with unparallelled space and time resolution. Early electrophysiological work was done largely in amphibians, because of their larger cell size, whereas studies in mammals were restricted to transepithelial electrical parameters, which provided no insight into individual membrane mechanisms. However, recently techniques have been developed to impale individual tubular cells of mammalian kidneys successfully, both in vivo and in vitro. Such experiments allow us to identify ion transport properties of individual cell membranes from the response of the electrical potential to fast pertubations of the luminal and/or peritubular fluid composition or to applied currents. The power of this approach was greatly increased by the development of ion-selective microelectrodes, allowing us to measure intracellular concentrations of Na+, K+, Cl-, Ca2+, and HCO3- or pH directly and to follow quantitatively their changes in response to different experimental maneuvers. In the present paper our knowledge of ion transport mechanisms of mammalian proximal tubular cell membranes is summarized, with emphasis on the transport of Na+, K+, HCO3-, and Cl-. With the exception of transcellular transport of Cl-, which is quantitatively less important, the major transport mechanisms of all other ions have been identified in the brush border and in the peritubular cell membrane. Emphasis is given to the description of HCO3- exit across the peritubular cell membrane, which has not thus far been studied with other than electrophysiological techniques. Microelectrode techniques will probably continue to provide new insight when regulatory phenomena are studied on the cellular level and individual conductance channels in renal cell membranes are identified with the newly developed patch-clamp technique.