Document Detail

Neutral Na-amino acid cotransport is differentially regulated by glucocorticoids in the normal and chronically inflamed rabbit small intestine.
MedLine Citation:
PMID:  17290012     Owner:  NLM     Status:  MEDLINE    
Neutral Na-amino acid cotransport by system ATB(0) [e.g., Na-alanine cotransport (NAcT)] is an important means of assimilation of amino acids in the intestine. NAcT is inhibited during chronic intestinal inflammation by an alteration in the affinity for the amino acid. How glucocorticoids, a standard of treatment for diseases characterized by chronic intestinal inflammation, may affect NAcT during chronic enteritis is not known. Thus we first demonstrated that methylprednisolone (MP) stimulated NAcT in the normal intestine. The mechanism of stimulation was secondary to an increase in cotransporter numbers without an alteration in the affinity for the amino acid. Treatment with MP reversed the reduction in NAcT in villus cells from the chronically inflamed intestine. MP also alleviated the decrease in Na-K-ATPase activity in villus cells during chronic enteritis. However, MP treatment reversed the NAcT inhibition in villus cell brush border membrane vesicles from the inflamed intestine, which suggested an effect of MP at the level of the cotransporter itself. Kinetic studies demonstrated that the reversal of NAcT inhibition by MP was secondary to restoration in the affinity for the amino acid without a change in the V(max). Unaltered steady-state mRNA and immunoreactive protein levels of NAcT also indicated that the number of cotransporters was unchanged after MP treatment in the chronically inflamed intestine. These results indicated that MP reversed NAcT inhibition in the chronically inflamed intestine by restoring the affinity of the transporter for the amino acid while it stimulated NAcT in the normal intestine by increasing the cotransporter numbers. Therefore, MP differentially regulates NAcT in the normal and chronically inflamed intestine.
Uma Sundaram; Sheik Wisel; Steven Coon
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  American journal of physiology. Gastrointestinal and liver physiology     Volume:  292     ISSN:  0193-1857     ISO Abbreviation:  Am. J. Physiol. Gastrointest. Liver Physiol.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-02-09     Completed Date:  2007-04-16     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  100901227     Medline TA:  Am J Physiol Gastrointest Liver Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  G467-74     Citation Subset:  IM    
Section of Digestive Diseases, Dept of Medicine, West Virginia Univ School of Medicine, Morgantown, WV 26506, USA.
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MeSH Terms
Alanine / metabolism
Amino Acid Transport System ASC / genetics,  metabolism*
Cell Membrane / drug effects,  metabolism
Disease Models, Animal
Enteritis / genetics,  metabolism*
Epithelial Cells / drug effects,  metabolism
Gene Expression / drug effects
Glucocorticoids / pharmacology*
Intestinal Mucosa / drug effects,  metabolism
Intestine, Small / drug effects,  metabolism*
Methylprednisolone / pharmacology
Microvilli / drug effects,  metabolism
Sodium / pharmacology
Sodium-Potassium-Exchanging ATPase / drug effects,  metabolism
Grant Support
Reg. No./Substance:
0/Amino Acid Transport System ASC; 0/Glucocorticoids; 56-41-7/Alanine; 7440-23-5/Sodium; 83-43-2/Methylprednisolone; EC ATPase

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