title: Electrical and freeze-fracture analysis of the effects of ionic cadmium on cell membranes of human proximal tubule cells.
abstract: We previously reported that cell cultures of human proximal tubule (HPT) cells respond to ionic cadmium in a manner consistent with well-defined Cd(2+)-elicited responses reported for in vivo systems. However, one unique finding was that the transepithelial electrical resistance and tight junction sealing strands were altered as a result of Cd2+ exposure at micromolar concentrations. These alterations are reexamined in detail in the present report to determine whether the Cd(2+)-induced alterations are specific alterations in the tight junction structure or reflect a general alteration in the cell membrane. Exhaustive analysis of tight junction sealing strands demonstrated no significant alterations due to Cd2+ exposure, even at the concentration that elicited a significant reduction in transepithelial resistance. Further analysis of intramembrane particle distribution demonstrated a significant increase in apical intramembrane particles, indicating that Cd2+ exposure altered the characteristics of the apical cell membrane. Overall, the results were consistent with evidence of Cd(2+)-induced alteration in the apical cell membrane of the HPT cell.
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston 29425.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hazen-Martin
authors.forename: J H
authors.initials: JH
authors.lastname: Todd
authors.forename: M A
authors.initials: MA
authors.lastname: Sens
authors.forename: W
authors.initials: W
authors.lastname: Khan
authors.forename: J E
authors.initials: JE
authors.lastname: Bylander
authors.forename: B J
authors.initials: BJ
authors.lastname: Smyth
authors.forename: D A
authors.initials: DA
authors.lastname: Sens
mesh_terms: D002104:Cadmium / Q000494:pharmacology*; D002413:Cations, Divalent / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017097:Electric Impedance; D005614:Freeze Fracturing; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D002104:Cadmium; D000242:Cyclic AMP; D000254:Sodium-Potassium-Exchanging ATPase