The electrophysiological analysis of tubular transport

Abstract

Although as early as 1935 Wilbrandt [1] made a first attempt to measure transepithelial potentials in Necturus kidney proximal tubule, the electrophysiological analysis of tubular transport began only in the late fifties, and it was not before the mid-seventies that well—defined information on the electrical phenomena associated with tubular transport became available. The reason for this slow development has been in part the methodological problems inherent in the technique which initially were only poorly understood. After these problems had been solved 121, however, the method has become an increasingly important tool in the hands of renal physiologists, and has contributed considerably to our present understanding of tubular transport phenomena and will undoubtedly continue to do so in the coming years. Much of this power is owed to the recent development of new methodological concepts such as ion—selective microlectrode techniques [3—7] and patch—clamp techniques [8, 91, which enable us not only to look into the tubular cell and follow changes in ion—activities, but also to directly observe single channel currents in cell membranes. I think it is fair to say that, with the exception of some optical measurements such as micro-fluorescence or cell volume measurements, there is presently no alternative approach available for studying ion transport events in normally functioning cells with comparable space and time resolution.