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 Ca(2+) 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 Ca(2+) 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.