Stimulation of intestinal glutamine absorption in chronic metabolic acidosis.
BACKGROUND
Amino acid glutamine plays a central role in inter-organ nitrogen transfer in acidosis, a compensatory mechanism that is essential in maintaining acidbase balance. Intestinal glutamine absorption is a key exogenous glutamine source in maintaining glutamine homeostasis. The purpose of this in vivo study was to investigate the regulation of intestinal glutamine absorption during chronic metabolic acidosis.


METHODS
Metabolic acidosis in adult male Sprague-Dawley rats was induced by adding 1.5% NH4Cl to drinking water. [3H]-L-glutamine transport activity across brush border membrane vesicles and glutamine transporter ATB0 messenger RNA levels by relative reverse transcriptase-polymerase chain reaction were measured in rat jejunum. Data were analyzed by t test (P < .05).


RESULTS
Acidosis occurred as early as 1 day and was partially compensated by 7 days. Glutamine transport in brush border membrane vesicles was increased after 2 days of acidosis. Chronic acidosis (7 days) resulted in an 8-fold increase of glutamine transport activity. The glutamine transport maximal capacity (Vmax) was stimulated 5-fold, while the transport affinity (Km) was not affected by acidosis. Relative reverse transcriptase-polymerase chain reaction showed a 2.5-fold increase of glutamine transporter ATB0 messenger RNA levels.


CONCLUSIONS
Chronic metabolic acidosis stimulates intestinal glutamine absorption via a mechanism that involves an increase of functional membrane glutamine transporter units.
Department of Surgery, The Milton S. Hershey Medical Center, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Ming
M
Pan
QingHe
Q
Meng
Haroon A
HA
Choudry
Anne M
AM
Karinch
ChengMao
C
Lin
Wiley W
WW
Souba
D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D002908:Chronic Disease; D005973:Glutamine / Q000378:metabolism*; D007408:Intestinal Absorption; D007583:Jejunum / Q000378:metabolism*; D008297:Male; D008871:Microvilli / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D005973:Glutamine