Transient receptor potential (TRP) channels are expressed in almost every segment of renal nephron from the glomerulus to the inner medullary collecting duct. Serving as a route for Ca2+ entry from the intratubular space into cells in response to external cues, TRP channels modulate water–electrolyte transport, thus determining functional properties of the renal tubule. In this chapter, we discuss technical aspects of using Ca2+ imaging to monitor activity of TRP channels in situ, namely, in the freshly isolated distal nephrons, with a special emphasis on the mechanosensitive TRPV4 channel and its role in tubular flow sensing.
