Evaluation of rat intestinal lactase in vivo with 4-galactosylxylose

Abstract

A deficiency of small intestinal lactase (EC 3.2.1.23) acting in adult type alactasia is the most frequent genetically based syndrome in man, affecting one-third to onehalf of the humans [l]. Its evaluation is important in pediatrics and gastroenterology. This can be carried out directly by mucosal sampling [2], or indirectly from blood glucose determination after a load of lactose [3], administration of lactose and ethanol and determination of galactose in blood [4], determination of 14C02 in the breath after ingestion of a small quantity of 14C-labelled lactose [5], measurement of either breath hydrogen [6,7] or urinary galactose [8] after lactose ingestion and determination of differential urinary excretion of disaccharides [9]. We have reported an entirely different, non-invasive evaluation procedure based on oral administration of 3-methyllactose followed by measurement of 3methylglucose in the urine [ 10,111. 3-Methyllactose proved to be an acceptable