Glucose-galactose malabsorption: demonstration of specific jejunal brush border membrane defect.
Jejunal brush border glucose transport was studied in a patient with glucose-galactose malabsorption and in controls, using jejunal brush border membrane vesicles (BBMV) prepared from conventional jejunal biopsies. Whereas BBMV from controls showed a seven-fold enhancement of D-glucose uptake in the presence of an inwardly directed sodium gradient compared with its absence, no such enhancement was seen in the patient's vesicles. In BBMV from the patient, initial D-glucose uptake under sodium gradient conditions was only 10% of the mean control value. In contrast, sodium/proton exchange in BBMV from the patient was intact. These data provide the first unequivocal evidence that the jejunal brush border membrane is the site of a specific defect in sodium dependent glucose transport in glucose-galactose malabsorption. Measurement of glucose uptake by BBMV may well be the optimal diagnostic technique in this disorder.
Booth
I W
IW
Institute of Child Health, University of Birmingham.
Patel
P B
PB
Sule
D
D
Brown
G A
GA
Buick
R
R
Beyreiss
K
K
D005690:Galactose / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D007583:Jejunum / Q000648:ultrastructure*; D008286:Malabsorption Syndromes / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008871:Microvilli / Q000378:metabolism
D005947:Glucose; D005690:Galactose