The effect of poorly absorbed solute on intestinal absorption.
To determine the effects of poorly absorbed solute on intestinal absorption, the urinary recovery of ingested lactulose, L-rhamnose, D-xylose, and 3-O-methyl-D-glucose was measured after simultaneous ingestion of various 'loads' of mannitol given in iso-osmolar solution. Mannitol reduced intestinal uptake of the poorly absorbed test sugars, lactulose and L-rhamnose; uptake of D-xylose and 3-O-methyl-D-glucose, which are absorbed by carrier-mediated transport largely from the jejunum, was less affected. The dose-response effect of mannitol on the absorption of L-rhamnose was approximately exponential; doses of 5, 10, and 20 g mannitol reduced the average urinary excretion of L-rhamnose by 34.7%, 51.7%, and 61.2%, respectively. In this respect, an osmotically equivalent load of lactulose, ingested as 'solute', was approximately twice as effective as mannitol in reducing L-rhamnose absorption, probably because lactulose is more poorly absorbed than mannitol (less than 1.0% versus 32-41%). Ingestion of other poorly absorbed solutes such as raffinose, sorbitol, xylitol, magnesium sulphate, and sodium sulphate also significantly depressed the absorption of L-rhamnose; in contrast, more efficiently absorbed solutes, such as sodium chloride, glucose, glycerol, and urea had little effect.
Menzies
I S
IS
Dept. of Chemical Pathology and Physiology, St Thomas' Hospital, London, U.K.
Jenkins
A P
AP
Heduan
E
E
Catt
S D
SD
Segal
M B
MB
Creamer
B
B
D019325:3-O-Methylglucose; D000328:Adult; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007792:Lactulose / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000008:administration & dosage / Q000494:pharmacology*; D008757:Methylglucosides / Q000378:metabolism; D008875:Middle Aged; D012210:Rhamnose / Q000378:metabolism; D012995:Solubility; D014994:Xylose / Q000378:metabolism
D008757:Methylglucosides; D019325:3-O-Methylglucose; D008353:Mannitol; D007792:Lactulose; D014994:Xylose; D012210:Rhamnose