Macula densa cell signaling.
Macula densa cells are renal sensor elements that detect changes in distal tubular fluid composition and transmit signals to the glomerular vascular elements. This tubuloglomerular feedback mechanism plays an important role in regulating glomerular filtration rate and blood flow. Macula densa cells detect changes in luminal sodium chloride concentration through a complex series of ion transport-related intracellular events. NaCl entry via a Na:K:2Cl cotransporter and Cl exit through a basolateral channel lead to cell depolarization and increases in cytosolic calcium. Na/H exchange (NHE2) results in cell alkalization, whereas intracellular [Na] is regulated by an apically located H(Na)-K ATPase and not by the traditional basolateral Na:K ATPase. Communication from macula densa cells to the glomerular vascular elements involves ATP release across the macula densa basolateral membrane through a maxi-anion channel. The adaptation of multi-photon microscopy is providing new insights into macula densa-glomerular signaling.
Bell
P Darwin
PD
Nephrology Research and Training Center, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. dbell@nrtc.uab.edu
Lapointe
Jean Yves
JY
Peti-Peterdi
János
J
D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D006801:Humans; D007606:Juxtaglomerular Apparatus / Q000166:cytology* / Q000502:physiology*; D007678:Kidney Glomerulus / Q000098:blood supply / Q000166:cytology* / Q000502:physiology*; D012079:Renal Circulation / Q000502:physiology