title: Morphologic alterations in the rat medullary collecting duct following potassium depletion.
abstract: Freeze-fracture and thin-section electron microscopy and morphometry were used to characterize further the response of the rat medullary collecting duct to potassium depletion. In freeze-fracture replicas, principal cells and intercalated cells were identified based on the assumption that intercalated cells possess a high density of rod-shaped intramembrane particles in their luminal membranes. Potassium depletion caused an increase in the relative number of cells with a high density of rod-shaped particles from the control level of 22% to 31% after 2 weeks and to 36% after 4 weeks. The frequency of intercalated cells identified by thin-section criteria was, however, about 35% in controls and unchanged by potassium depletion. This suggests that intercalated cells can have two types of membrane morphology. In potassium depletion, all intercalated cells display a high density of rod-shaped particles in their luminal membranes. In addition, the luminal membrane area of intercalated cells increased more than threefold, and the density of their rod-shaped particles increased by 21%. These observations suggest that the intercalated cell and its rod-shaped particle may be involved with the potassium reabsorption that occurs in this nephron segment with potassium depletion.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing; D007679:Kidney Medulla / Q000502:physiology* / Q000648:ultrastructure; D007684:Kidney Tubules / Q000473:pathology*; D007685:Kidney Tubules, Collecting / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D009940:Organoids / Q000648:ultrastructure; D011188:Potassium / Q000378:metabolism*; D011191:Potassium Deficiency; D051381:Rats
chemical_list: D011188:Potassium