Document Detail


Kinetic constants for blood-brain barrier amino acid transport in conscious rats.
MedLine Citation:
PMID:  4045456     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The kinetic constants for large neutral amino acid (LNAA) transport across the blood-brain barrier (BBB) of conscious rats were determined in four brain regions: cortex, caudate-putamen, hippocampus, and thalamus-hypothalamus. Indwelling external carotid artery catheters allowed for single-bolus (200 microliters) injections directly into the arterial system of unanesthetized and lightly restrained animals. Our results showed lower brain uptake index values for conscious rats compared to previous reports for anesthetized animals which are consistent with higher rates of cerebral blood flow in the conscious animals. Km values were lower in the conscious animals and ranged from 29% to 87% of the Km values in pentobarbital-anesthetized animals whereas the KD values were about twofold higher in the conscious animals. No apparent regional differences were observed. Influx rates were determined which take into consideration flow rates and plasma amino acid concentrations. Our results showed an average amino acid influx value of 5.2 nmol/min/g, which is 53% higher than the average influx in pentobarbital-anesthetized animals. The present results in conscious animals regarding the low Km of LNAA transport across the BBB lend further support to the importance of fluctuations in plasma amino acid concentrations and LNAA transport competitive effects on brain amino acid availability.
Authors:
L P Miller; W M Pardridge; L D Braun; W H Oldendorf
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of neurochemistry     Volume:  45     ISSN:  0022-3042     ISO Abbreviation:  J. Neurochem.     Publication Date:  1985 Nov 
Date Detail:
Created Date:  1985-11-18     Completed Date:  1985-11-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985190R     Medline TA:  J Neurochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1427-32     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amino Acids / blood,  metabolism*
Animals
Biological Transport
Blood-Brain Barrier*
Carbon Radioisotopes
Consciousness / physiology*
Kinetics
Mathematics
Rats
Rats, Inbred Strains
Tritium
Grant Support
ID/Acronym/Agency:
AM-00783/AM/NIADDK NIH HHS; R01-NS 19271/NS/NINDS NIH HHS
Chemical
Reg. No./Substance:
0/Amino Acids; 0/Carbon Radioisotopes; 10028-17-8/Tritium

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


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