Document Detail


Contraluminal transport of organic cations in the proximal tubule of the rat kidney. I. Kinetics of N1-methylnicotinamide and tetraethylammonium, influence of K+, HCO3-, pH; inhibition by aliphatic primary, secondary and tertiary amines and mono- and bisquaternary compounds.
MedLine Citation:
PMID:  1834988     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In order to study the characteristics of contraluminal organic cation transport from the blood site into proximal tubular cells the stopped-flow capillary perfusion method was applied. The disappearance of N1-[3H]methylnicotinamide (NMeN+) and [3H]tetraethylammonium (TEA+) at different concentrations and contact times was measured and the following parameters evaluated: Km,NMeN = 0.54 mmol/l, Jmax,NMeN = 0.4 pmol s-1 cm-1; Km,TEA = 0.16 mmol/l, Jmax,TEA = 0.8 pmol s-1 cm-1. TEA+ inhibited NMeN+ transport and NMeN+ the uptake of TEA+. Thereby, the Ki values for inhibition correspond closely to the Km values for uptake. Similar inhibitory potencies of ten organic cation against TEA+ and NMeN+ transport provide further evidence for a common transport system. Omission of HCO3-, or Na+ and addition of K+ (with or without Ba2+) reduce NMeN+ transport, while omission of K+ (with or without valinomycin) or addition of thiocyanate has no effect. Since the manoeuvres that depolarize contraluminal electrical potential difference reduce NMeN+ transport, cell-negative electrical potential difference is suggested as a driving force for contraluminal organic cation transport from the interstitium into the cell. Furthermore, the inhibitory potency (app. Ki values) of homologous series of primary, secondary, tertiary and hydroxy amines as well as of mono- and bisquaternary ammonium compounds against NMeN+ transport was tested. The inhibitory potency increased in the sequence methyl less than ethyl less than propyl less than butyl and primary less than secondary less than tertiary amines less than quaternary ammonium compounds.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
K J Ullrich; F Papavassiliou; C David; G Rumrich; G Fritzsch
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  419     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  1991 Aug 
Date Detail:
Created Date:  1991-11-29     Completed Date:  1991-11-29     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  84-92     Citation Subset:  IM    
Affiliation:
Max-Planck-Institut für Biophysik, Frankfurt/Main, Federal Republic of Germany.
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MeSH Terms
Descriptor/Qualifier:
Amines / pharmacology
Animals
Bicarbonates / pharmacology
Biological Transport / drug effects
Cations / antagonists & inhibitors,  pharmacokinetics*
Hydrogen-Ion Concentration
Kidney Tubules, Proximal / metabolism*
Male
Niacinamide / analogs & derivatives,  pharmacokinetics
Potassium / pharmacology
Quaternary Ammonium Compounds / pharmacology
Rats
Rats, Inbred Strains
Tetraethylammonium
Tetraethylammonium Compounds / pharmacokinetics
Chemical
Reg. No./Substance:
0/Amines; 0/Bicarbonates; 0/Cations; 0/Quaternary Ammonium Compounds; 0/Tetraethylammonium Compounds; 114-33-0/N-methylnicotinamide; 66-40-0/Tetraethylammonium; 7440-09-7/Potassium; 98-92-0/Niacinamide

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


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