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A model for fluid secretion in the exocrine pancreas
G A Kuijpers1, J J De Pont, H V Westerhoff
1Laboratory of Cell Biology and Genetics, NIDDK, Bethesda, MD.
Biochimica Et Biophysica Acta
|August 21, 1989
Summary
Rabbit pancreas fluid secretion relies on sodium (Na+). Replacing Na+ with other ions like lithium (Li+) or potassium (K+) alters secretion. A model explains these Na+-dependent fluid and ion transport mechanisms.
Area of Science:
- Physiology
- Biophysics
- Cell Biology
Background:
- Pancreatic fluid secretion is crucial for digestion.
- Sodium ions (Na+) play a key role in regulating pancreatic fluid and electrolyte secretion.
- Understanding the precise mechanisms of ion transport is vital for comprehending pancreatic function.
Purpose of the Study:
- To develop a quantitative model for pancreatic ion and water secretion.
- To elucidate the roles of Na+-dependent transport and paracellular permeability.
- To investigate the effects of Na+ substitution and secretagogue stimulation on pancreatic secretion.
Main Methods:
- Utilized an isolated rabbit pancreas model.
- Performed ion substitution experiments (Na+ with Li+ or K+).
- Applied stimulatory agonists like CCK-8 and carbachol.
- Developed and analyzed a quantitative model of ion and water transport.
Main Results:
- Pancreatic fluid secretion is highly dependent on extracellular Na+ concentration.
- Na+ substitution with Li+ or K+ inhibited secretion and altered secreted fluid composition.
- Stimulation increased paracellular ion permeability and modulated fluid secretion.
- The model accurately predicted observed effects of Na+ substitution and stimulation.
Conclusions:
- Pancreatic secretion involves active, Na+-dependent transcellular bicarbonate (HCO3-) transport.
- Passive, paracellular movement of ions contributes to fluid secretion.
- Paracellular ion permeability is modulated by secretagogues.
- The model provides insights into the control of pancreatic secretion by system and external parameters.