Intestinal Absorption of Sucrose in Man: The Site of Hydrolysis and Absorption*

Gray, Gary M.; Ingelfinger, Franz J.

doi:10.1172/jci105152

Cited by 72 publications

(26 citation statements)

References 24 publications

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“…The aspiration opening was held at 80, 120, or 200 cm away from the teeth for perfusion studies in the duodenum, jejunum, or ileum respectively. These distances have been previously selected for perfusion studies in man (4,15 (17) and between 100-140 mm sodium 2 Model 600-1200, the Harvard Apparatus Co., Millis, Mass.…”

Section: Methodsmentioning

confidence: 99%

Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption

Adibi¹,

Morse²

1971

J. Clin. Invest.

310

163

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A 30 cm segment of the duodenum, jejunum, or ileum of normal human volunteers was perfused, on separate occasions, with test solutions containing either glycylglycine, free glycine, glycylleucine, or equimolar amounts of free glycine and free leucine. Luminal fluid contained no hydrolytic activity against glycylglycine and minimal activity against glycylleucine. In each intestinal segment, amino acid absorption rates were significantly greater from the test solutions containing the same amount of amino acids in dipeptide than in free form (as high as 185% increase). Perfusion of each intestinal segment with a test solution containing the equimolar mixture of free glycine and free leucine always resulted in a greater leucine than glycine absorption rate. This preferential absorption of leucine, however, was either diminished (jejunum) or almost abolished (duodenum and ileum) when the glycylleucine solution instead of the equimolar mixture was presented to the intestinal mucosa. Among the three segments, the duodenum exhibited the least potential for the disappearance of dipeptides. The jejunal and ileal dipeptide disappearance rates were either similar for glycylleucine (94% vs. 92%) or slightly different for glycylglycine (92% vs. 79%). Despite lack of a remarkable difference in the disappearance rates, absorption rates of constituent amino acids were markedly greater in the jejunum than in the ileum. This reduced amino acid absorption was brought about by a greater accumulation of free amino acids in the lumen of the ileal segment in the lumen than when the glycylglycine test solution did not contain free leucine. Similarly, inhibition of free glycine and free leucine absorption by isoleucine was not accompanied by any remarkable alteration of absorption rates of the constituent amino acids of glycylleucine. The results of these studies suggest that: (a) dipeptide disappearance in the gut lumen is principally accomplished by intact absorption and not by hydrolysis; (b) intracellular hydrolysis of dipeptides is markedly greater in the ileum than in the jejunum, while dipeptide absorption rates are either similar or only slightly different in these two segments; (c) there is no appreciable hydrolysis of glycylglycine by the membrane-bound enzymes and only a small fraction of glycylleucine is hydrolyzed by these enzymes.

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Section: Methodsmentioning

confidence: 99%

Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption

Adibi¹,

Morse²

1971

J. Clin. Invest.

310

163

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“…Although intestinal glucose concentrations after normal meals have never been directly measured, it has been thought that most glucose absorption in man occurs against a concentration gradient (31). However, an appreciable amount of starch is hydrolyzed to glucose by amylase (32), and it is thought that at least a significant fraction of the glucose produced by sucrose hydrolysis escapes from the site of hydrolysis on the mucosal surface and returns to the intestinal lumen (25). to determine whether luminal concentrations of glucose in man ever reached levels such that downhill transport could occur.…”

Section: Methodsmentioning

confidence: 99%

The role of sodium in intestinal glucose absorption in man

Olsen¹,

Ingelfinger²

1968

J. Clin. Invest.

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“…The presence of serum maltase activity sug- (18,19) have shown that the rates of hydrolysis for sucrose and maltose are appreciably greater than the rate for lactose and that lactose hydrolysis is rate limiting for over-all lactose absorption.…”

Section: Introductionmentioning

confidence: 99%

Metabolism of Circulating Disaccharides in Man and the Rat *

Weser¹,

Sleisenger²,

Dickstein³

et al. 1967

J. Clin. Invest.

103

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Summary. The metabolism of circulating disaccharides was studied in adult humans and rats. After iv infusions of 10 g of either lactose, sucrose, or maltose in four adults, no rise in blood glucose was noted. A mean of 8.7 + 1.89 g of the lactose and 6.3 + 1.39 g of the sucrose was excreted in the 24-hour urine sample. Only 0.11 ± 0.03 g of the infused maltose was recovered in the urine, suggesting that the maltose was metabolized.After injection of 14C-labeled lactose and sucrose in rats, 6.2 + 2.7 and 7.6 ± 2.4%, respectively, was oxidized to 14CO2 in 24 hours; 62.1 ± 13.5 and 68.4 ± 10.8% of the respective disaccharides was excreted into the urine. Conversely, after injection of 14C-labeled maltose 54.6 + 7.0% was oxidized to 14CO0 and 4.8 + 3.9% excreted in the urine. The per cent of maltose oxidized to CO2 was similar to that of glucose.In addition to small intestinal mucosa, homogenates of rat kidney, brain, and liver as well as serum were found to have measurable maltase activities.

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Intestinal Absorption of Sucrose in Man: The Site of Hydrolysis and Absorption*

Cited by 72 publications

References 24 publications

Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption

Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption

The role of sodium in intestinal glucose absorption in man

Metabolism of Circulating Disaccharides in Man and the Rat *

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