Document Detail

Origin of positive transepithelial potential difference in early distal segments of rat kidney.
MedLine Citation:
PMID:  4010149     Owner:  NLM     Status:  MEDLINE    
Previous studies from our laboratory indicate that early distal segments of the rat kidney have a positive transepithelial potential difference (PD). The present study investigates the origin of the positive PD. PDs were measured in early distal segments using a technique which allowed simultaneous microperfusion and PD measurement through a single pipette (3 to 6 micron O.D.). Microperfusion with artificial plasma ultrafiltrate resulted in a significantly negative mean PD of -4.9 +/- 0.7 mV (N = 17), in contrast to a positive free-flow PD of +5.7 +/- 1.1 mV (N = 174) (P less than 0.001). Addition of amiloride 10(-4) M to plasma ultrafiltrate changed the PD to +1.7 +/- 0.2 mV (N = 25, P less than 0.001). In contrast, furosemide 10(-4) M had no effect on the perfusion PD. Removal of sodium from the luminal perfusate abolished any effect of amiloride on the perfusion PD. Perfusion with artificial early distal fluid yielded a positive PD of +4.2 +/- 0.2 mV (N = 19). Amiloride increased this PD to +8.3 +/- 0.7 mV (N = 21, P less than 0.001). Subsequent experiments in which the sodium and potassium concentrations of the perfusates were varied indicated that concentration gradients for these ions across the early distal tubule could generate substantial diffusion PDs and that potassium was much more permeant than sodium.(ABSTRACT TRUNCATED AT 250 WORDS)
G G Allen; L J Barratt
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Kidney international     Volume:  27     ISSN:  0085-2538     ISO Abbreviation:  Kidney Int.     Publication Date:  1985 Apr 
Date Detail:
Created Date:  1985-08-22     Completed Date:  1985-08-22     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  0323470     Medline TA:  Kidney Int     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  622-9     Citation Subset:  IM    
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MeSH Terms
Amiloride / pharmacology
Biological Transport, Active / drug effects
Cell Membrane Permeability
Chlorides / pharmacology
Epithelium / physiology
Kidney Tubules / physiology*
Kidney Tubules, Distal / drug effects,  physiology*
Membrane Potentials
Potassium / metabolism,  pharmacology
Rats, Inbred Strains
Sodium / metabolism,  pharmacology
Reg. No./Substance:
0/Chlorides; 2609-46-3/Amiloride; 7440-09-7/Potassium; 7440-23-5/Sodium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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