Ion transport across isolated pig jejunum

Area of Science:

• Physiology
• Biochemistry

Background:

• Intestinal epithelial transport is crucial for nutrient and electrolyte absorption.
• Understanding the mechanisms of sodium and glucose cotransport is vital for physiological studies.

Purpose of the Study:

• To investigate the mechanisms of sodium, chloride, and glucose transport in pig jejunal epithelium.
• To determine the role of sodium-glucose cotransport in net sodium absorption.
• To analyze the influence of glucose concentration on ion transport.

Main Methods:

• Utilized stripped pig jejunal epithelium mounted in Ussing chambers.
• Measured unidirectional fluxes and transepithelial electrical potential.
• Applied Michaelis-Menten kinetics to analyze glucose-dependent transport.
• Investigated the effects of ion substitution (2-hydroxyethanesulfonate) and pharmacological agents (theophylline).

Main Results:

• Net sodium absorption is electrogenic and exclusively mediated by sodium-glucose cotransport.
• Michaelis-Menten analysis yielded glucose-dependent Michaelis constants of 1.5 mM for influx and 9.6 mM for glucose.
• Chloride absorption was driven by the electrical potential generated by sodium-glucose cotransport.
• Theophylline induced chloride secretion, indicating active transport mechanisms.

Conclusions:

• Sodium-glucose cotransport is the primary driver of sodium absorption in pig jejunum.
• Chloride transport is passively influenced by the electrical gradient established by sodium-glucose cotransport.
• The pig jejunal epithelium exhibits stable transport characteristics suitable for physiological research.