1. The jejunal absorption of glucose from (1–4)-linked glucose oligomers including maltotriose has been compared with that from free glucose and sucrose in normal subjects. 2. A steady-state perfusion technique in vivo was used to study proximal jejunal assimilation of isotonic sugar-saline solutions isocaloric with 140 mmol/l glucose. Endogenous α-amylase was excluded from the test segment by proximal balloon occlusion. The glucose oligomer mixture consisted mainly of maltotriose, maltotetraose, maltopentaose and maltoheptaose. 3. Glucose absorption was significantly faster from maltotriose alone and from the glucose oligomer mixture than from 140 mmol/l glucose controls, whereas glucose absorption from 70 mmol/l sucrose was similar to that from 70 mmol/l glucose plus 70 mmol/l fructose. 4. Hydrolysis in vivo of maltotriose, the oligomer mixture and sucrose were similar, indicating that capture of glucose released by brush border sucrose hydrolysis was less efficient than that associated with (1–4)-linked oligomer hydrolysis. This suggests that the stoichiometric relationship of the active hydrolysis sites for sucrose to the glucose transport system is less advantageous than that of active sites for maltose hydrolysis. 5. Hydrolysis of oligomers larger than maltohexaose may be rate limiting for glucose absorption in the absence of luminal amylase activity.
1. A double lumen jejunal perfusion technique has been used in man to study the effect of peptide chain length on absorption of amino acid nitrogen from two partial enzymic hydrolysates of lactalbumin. 2. Copper-chelation chromatography showed that one lactalbumin hydrolysate (LH2) contained 98% peptides with a chain length > 4, whilst the other (LH1) contained a more even spread of chain lengths with 55% <4. 3. Absorption of total nitrogen and of 14 amino acid residues occurred to a significantly greater extent from the low molecular weight LH1 than from the higher molecular weight LH2. 4. The results suggest that the pattern of nitrogen and amino acid absorption from partial enzymic hydrolysates of whole protein is markedly influenced by peptide chain length and that brush border peptide hydrolysis has an important rate limiting effect on absorption rates.
1. A steady-state perfusion technique has been used in vivo in normal subjects to show that at concentrations occurring during therapeutic use (500 mg/l, 1.1 mmol/l) the antibiotic clindamycin reversibly inhibits bicarbonate-stimulated water and electrolyte absorption from the human jejunum. 2. Lactose-stimulated water and electrolyte absorption was not affected by the addition of clindamycin at the same concentration. 3. Clindamycin-induced malabsorption of water and electrolytes may contribute significantly to the diarrhoea that occurs during clindamycin therapy in the absence of pseudomembranous colitis.