Interpretation of disaccharide-dependent electrical potential differences in the small intestine

Area of Science:

• Physiology
• Biochemistry
• Molecular Biology

Background:

• Disaccharides like maltose and trehalose are important dietary sugars.
• Understanding sugar absorption mechanisms is crucial for metabolic and digestive health.

Purpose of the Study:

• To investigate the electrical potential changes induced by maltose and trehalose in toad small intestines.
• To elucidate the relationship between disaccharidase activity and hexose transport.

Main Methods:

• Everted small intestine sacs from toads were used to measure electrical potential differences (PD).
• Disaccharide concentrations were varied, and Michaelis-Menten and Lineweaver-Burk kinetics were analyzed.
• The effects of phlorizin and Tris buffer were assessed.

Main Results:

• Disaccharide-induced potential increments (deltaPD) followed Michaelis-Menten-like kinetics.
• Kinetic plots deviated at higher concentrations, suggesting complex transport mechanisms.
• Disaccharide- and glucose-evoked potentials were non-additive and phlorizin-sensitive.
• Tris buffer inhibited disaccharide-evoked potentials, mirroring enzyme activity inhibition.

Conclusions:

• A functional linkage exists between brush border disaccharidase activity and electrogenic hexose transport.
• A local glucose pool at the brush border helps explain the observed electrical potential changes.
• Disaccharide-evoked potentials provide insights into intestinal sugar absorption processes.