Sequential alterations in gut mucosal amino acid and glucose transport after 70% small bowel resection.
BACKGROUND
Studies in animals with short bowel syndrome (SBS) suggest that up-regulation of nutrient transporter activity occurs as an adaptive response to the loss of absorptive area. It is unclear, however, whether nutrient transport is altered at the cell membrane in SBS. The purpose of this study is to clarify amino acid and glucose transport in small intestinal luminal mucosa after 70% small bowel resection in rabbits.


METHODS
New Zealand white rabbits underwent 70% jejunoileal resection (n = 27) or a sham operation (n = 19). Brush border membrane vesicles were prepared from small intestinal mucosa at 1 week, 1 month, and 3 months by magnesium aggregation-differential centrifugation. Transport of L-glutamine, L-alanine, L-leucine, L-arginine, and D-glucose was assayed by a rapid mixing-filtration technique.


RESULTS
We observed no difference in uptake of all amino acids and glucose at 1 week. The uptake of amino acids and glucose was decreased by 20% to 80% in animals with SBS at 1 month. By 3 months all uptake values except that of glucose returned to normal. Kinetic studies of the system B transporter for glutamine indicate that the decrease in uptake at 1 month was caused by a reduction in the Vmax (1575 +/- 146 versus 2366 +/- 235, p < 0.05) consistent with a decrease in the number of functional carriers on the brush border membrane.


CONCLUSIONS
In addition to the anatomic loss of absorptive area after massive bowel resection, alterations in enterocyte transport function may be responsible for malabsorption in patients with SBS.
Sarac
T P
TP
Department of Surgery, University of Rochester Medical Center, NY 14642-8410, USA.
Seydel
A S
AS
Ryan
C K
CK
Bessey
P Q
PQ
Miller
J H
JH
Souba
W W
WW
Sax
H C
HC
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D005947:Glucose / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000648:ultrastructure; D007421:Intestine, Small / Q000601:surgery*; D008297:Male; D008871:Microvilli / Q000378:metabolism; D011817:Rabbits
D000596:Amino Acids; D005947:Glucose