Characterization of ischemia-induced loss of epithelial polarity

• Published in: The Journal of membrane biology 1988-12, Vol.106 (3), p.233-242
• Main Authors: MOLITORIS, B. A, HOILIEN, C. A, DAHL, R, AHNEN, D. J, WILSON, P. D, JIN KIM
• Format: Article
• Language: English
• Subjects: Adenylyl Cyclases - metabolism; Animals; Biological and medical sciences; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; Electrophoresis, Polyacrylamide Gel; Epithelium - metabolism; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Intracellular Membranes - metabolism; Ischemia - metabolism; kidney; Kidney - blood supply; Leucyl Aminopeptidase - analysis; Male; membrane lipids; Membrane Lipids - analysis; membrane proteins; Membrane Proteins - analysis; Microscopy, Electron; Molecular and cellular biology; proximal tubules; Rats; Rats, Inbred Strains; Sodium-Potassium-Exchanging ATPase - analysis; Staining and Labeling
• ISSN: 0022-2631; 1432-1424
• DOI: 10.1007/BF01872161

Total renal ischemia for various time intervals (0-50 min) resulted in the rapid and duration-dependent redistribution of polarized membrane lipids and proteins in renal proximal tubule cells. Following only 15 min of ischemia, apical membrane enrichment of NaK-ATPase, normally a basolateral membrane (BLM) enzyme, had increased (1.6 +/- 0.6 vs. 2.9 +/- 1.2, P less than 0.01). In vivo histochemical localization of NaK-ATPase showed reaction product throughout the apical microvillar region. PTH-stimulatable adenylate cyclase, another BLM protein, was also found in ischemic but not control apical membrane fractions. One dimensional SDS-PAGE showed four bands, present in control BLM and ischemic apical membranes, which could not be found in control apical membrane fractions. Immunohistochemical localization of leucine aminopeptidase (LAP) showed the enzyme was limited to the apical domain in control cells. Following ischemic injury (50 min), LAP staining could be seen within the cell and along the BLM. Following 24 hr of reperfusion, the BLM distribution of LAP was further enhanced. With cellular recovery from ischemic injury (5 days), LAP was again only visualized in the apical membrane. Duration-dependent alterations in apical and BLM lipids were also observed. Apical sphingomyelin and phosphatidylserine and the cholesterol-to-phospholipid ratio decreased rapidly while apical phosphatidylcholine and phosphatidylinositol increased. Taken together, these results indicate renal ischemia causes rapid duration-dependent reversible loss of surface membrane polarity in proximal tubule cells.