Evidence for voltage-dependent C1- permeability in mouse pancreatic beta-cells

Area of Science:

• Endocrinology
• Cell Physiology
• Molecular Biology

Background:

• Pancreatic beta-cells regulate glucose homeostasis through insulin secretion.
• Chloride (Cl-) transport plays a crucial role in beta-cell function and excitability.
• Understanding Cl- flux mechanisms is vital for metabolic disease research.

Purpose of the Study:

• To investigate the role of transmembrane 36Cl- efflux in pancreatic beta-cells.
• To determine the effect of membrane depolarization and glucose on Cl- permeability.
• To elucidate the mechanisms underlying glucose-stimulated Cl- transport.

Main Methods:

• Utilized microdissected beta-cell-rich pancreatic islets from ob/ob-mice.
• Measured transmembrane 36Cl- efflux rates under varying extracellular K+ concentrations.
• Assessed the impact of glucose (20 mM) on 36Cl- efflux.

Main Results:

• A stable rate coefficient for 36Cl- efflux was observed (0.158 min-1).
• Extracellular K+ (5-130 mM) stimulated 36Cl- efflux concentration-dependently, indicating voltage-dependent Cl- permeability.
• Glucose- and K+-induced efflux were similar, but glucose further enhanced efflux at high K+.

Conclusions:

• Pancreatic beta-cells possess voltage-dependent Cl- permeability.
• Glucose-induced Cl- permeability increase may involve initial membrane depolarization.
• Additional glucose-activated mechanisms likely contribute to beta-cell Cl- transport.