K depletion and NH4Cl acidosis increase apical insertion of studded membrane in type A intercalated cells.
To examine the effects of K depletion and metabolic acidosis on the prevalence and distribution of H(+)-adenosinetriphosphatase (H(+)-ATPase)-related studs at the luminal plasma membrane of A-type intercalated cells (A-ICs), we conducted a quantitative electron microscopical study on the cortical collecting ducts (CCDs) of control, NH4Cl-loaded, and K-depleted rats. The percentage of A-ICs was slightly increased in the K-depleted but not in the acidotic rats. A-ICs were considered "active" when they presented a semicontinuous row of 9- to 10-nm studs at the cytoplasmic face of the apical membrane and "inactive" when all of the apical membrane was devoid of studs. The percentage of active A-ICs was greatly increased in acidotic (87.2%) and K-depleted (79.3%) rats compared with controls (41.6%). These results give a quantitative expression to the general view that acidosis elicits insertion of studded membrane in the apical plasma membrane of A-ICs. Furthermore, we show, for the first time, that an increase in the membrane insertion of H(+)-ATPase is also part of the response to K depletion.
Narbaitz
R
R
Department of Anatomy and Neurobiology, University of Ottawa, Ontario, Canada.
Murugesan
S
S
Levine
D Z
DZ
D000138:Acidosis / Q000139:chemically induced / Q000473:pathology*; D000643:Ammonium Chloride; D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D007685:Kidney Tubules, Collecting / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D011191:Potassium Deficiency / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000643:Ammonium Chloride