Document Detail

Renal tubular transport of folic acid and methotrexate in the monkey.
MedLine Citation:
PMID:  7081435     Owner:  NLM     Status:  MEDLINE    
The renal excretion of folic acid and methotrexate (MTX) was investigated in pentobarbital-anesthetized cynomolgus, rhesus, and AFrican green monkeys by standard clearance and stop-flow techniques. The renal clearance of folic acid was below inulin clearance at all plasma concentrations studied; the (U/P)folic/(U/P)In ratio increased from 0.26 at a concentration of 0.03 mM to a plateau value of 0.9 at concentrations above 0.2 mM, indicating net reabsorption by a saturable system. In stop-flow experiments, base-line (U/P)folic/(U/P)In ratios during free-flow periods were below 1.0, but increased by twofold in stop-flow samples derived from the proximal tubule, indicating net secretion during stopped flow. The stop-flow pattern of MTX excretion was similar, except the base-line flow pattern of MTX excretion was similar, except the base-line (U/P)MTX/(U/P)In ratio exceeded 1.0, indicating net secretion during both free-flow and stopped-flow periods. Secretion of both compounds was inhibited by p-aminohippuric acid and other organic acids but not by L-glutamic acid. It is concluded that folic acid is transported bidirectionally, while evidence was obtained only for secretion of MTX.
W M Williams; K C Huang
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  242     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1982 May 
Date Detail:
Created Date:  1982-07-08     Completed Date:  1982-07-08     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  F484-90     Citation Subset:  IM    
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MeSH Terms
Biological Transport
Cercopithecus aethiops
Folic Acid / metabolism*
Kidney Tubules / metabolism*
Kidney Tubules, Proximal / metabolism
Macaca fascicularis
Macaca mulatta
Metabolic Clearance Rate
Methotrexate / metabolism*
Proteins / metabolism
Grant Support
Reg. No./Substance:
0/Proteins; 59-05-2/Methotrexate; 59-30-3/Folic Acid

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

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