Cross-talk and the role of KATP channels in the proximal tubule.

Over the last few years it has become evident that an assortment of functionally-related, but diverse, KATP channels provide an important and physiologically-regulated determinant of the K conductive pathways in many, if not all, epithelial cells expressed along the nephron. As such, KATP plays central roles in regulating and maintaining a number of transport processes in concert with physiological demands of the kidney. In the renal proximal tubule, KATP channels and changes in the hydrolytic activity of the Na,K-ATPase permit ATP to act as a coupling modulator of parallel Na,K-ATPase-K recycling. The response insures that cell membrane potential, intracellular K activity and cell volume are protected in the face of physiological variations in transcellular ion transport. In addition to demonstrating the physiological relevance of KATP in renal epithelial, these studies have provided a long awaited answer to the underlying mechanism of pump-leak coupling, a universal and essential homeostatic mechanism observed in nearly all salt translocating epithelia.