The exsorption characteristics of various sugars

Area of Science:

• Gastroenterology
• Physiology
• Biochemistry

Background:

• Understanding sugar transport across the intestinal barrier is crucial for metabolic and digestive health.
• The selective permeability of the intestinal mucosa to various carbohydrates is not fully elucidated.

Purpose of the Study:

• To investigate the exsorption rates of different sugars from plasma to the intestinal lumen in rabbits.
• To identify factors influencing the intestinal barrier's permeability to sugars, particularly glucose and galactose.

Main Methods:

• Intravenous administration of various sugars (lactulose, mannose, xylose, glucose, galactose) to rabbits.
• Measurement of sugar exsorption rates from plasma into the intestinal lumen.
• Assessment of the effect of luminal phlorizin, actively absorbed sugars, 2,4-dinitrophenol, and sodium ion absence on the mucosal barrier.

Main Results:

• Exsorption rates of lactulose, mannose, and xylose correlated with plasma concentration and molecular weight.
• Glucose and galactose showed limited exsorption until very high plasma concentrations were achieved, indicating a mucosal barrier.
• This barrier was abolished by luminal phlorizin or actively absorbed sugars, but not by 2,4-dinitrophenol or sodium ion absence.
• Elevated plasma glucose concentrations eventually led to rapid glucose exsorption into the lumen.

Conclusions:

• The intestinal barrier exhibits selective permeability to sugars, influenced by plasma concentration and molecular weight.
• Specific mechanisms, potentially involving active transport or carrier proteins, regulate glucose and galactose exsorption.
• The findings provide insights into intestinal sugar absorption regulation and potential therapeutic targets.