title: Distal urinary acidification from Homer Smith to the present.
abstract: Since Smith's time, the essential role of collecting duct intercalated cells in controlling net acid excretion has been recognized. Rather than employing an H(+)-exchange mechanism, intercalated cells have V-ATPase on the plasma membrane and in plasmalemma-associated tubulovesicles, which functions in the bicarbonate reabsorption, regeneration, and bicarbonate secretion required for acid-base homeostasis. Several distinct mechanisms participate in regulating V-ATPase-driven H+ secretion in different cell types: (1) Renal epithelial cells have the capacity to express different structural forms of V-ATPase that have intrinsic differences in their enzymatic properties. 2) The kidney produces cytosolic regulatory proteins, capable of interacting directly with the V-ATPase, that may modify its activity. V-ATPases in different cell types may differ in the degree to which their activity is affected by regulatory factors, as a result of variations in V-ATPase structure. (3) In the alpha intercalated cell, the number of active V-ATPases on the luminal membrane is controlled in vivo by membrane vesicle-mediated traffic that may require unidentified mediators. In the beta intercalated cell, the number of active V-ATPases on the basolateral membrane may be controlled by regulated assembly and disassembly, responding directly to extracellular pH.
authors: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA. sgluck@imgate.wustl.edu
authors: S L
authors: SL
authors: Gluck
authors: M
authors: M
authors: Iyori
authors: L S
authors: LS
authors: Holliday
authors: T
authors: T
authors: Kostrominova
authors: B S
authors: BS
authors: Lee
mesh_terms: D000143:Acids / Q000652:urine*; D000818:Animals; D049673:History, 20th Century; D007668:Kidney / Q000502:physiology / Q000648:ultrastructure; D007686:Kidney Tubules, Distal / Q000502:physiology*; D009398:Nephrology / Q000266:history; D010828:Physiology, Comparative / Q000639:trends
chemical_list: D000143:Acids