16. DEMONSTRATTCN OF DEFECTIVE JEJUNAL BRUSH BORDER Na+-COUPLED GLUCOSE TRANSPORT IN CONGENITAL GLUCOSE-GALACTCSE MALABSORPTION

摘要

Studies in congenital glucose-galactose malabsorption (GGM) have indicated an abnormality in small intestinal glucose and galactose transport but the precise site of the defect has not been defined. We have therefore investigated Na+-coupled D-glucose uptake, and Na+/H+ exchange in a patient with GGM using brush border membrane vesicles (BBMV) prepared from jejunal biopsies using a miniaturised Mg++-precipitation technique. The diagnosis was confirmed by clinical presentation, response to diet and jejunal perfusion studies, which showed markedly defective glucose and galactose absorption (p +-gradient (100mmol/l) enhanced 15 sec D-glucose uptake × 5.5 (p + (p +/H+ exchange was intact, with a 6-fold enhancement of Na+ uptake by an outwardly directed H+ gradient (pH in: 6.0; out: 7,4) at 15 sec.These studies therefore confirm for the first time, that a defect in brush border Na+-coupled glucose uptake is present in GGM, and suggest that BBMV studies may be the optimal technique for confirmation of the diagnosis.