Glucose metabolism in mouse pancreatic islets

Area of Science:

• Biochemistry
• Cell Biology
• Endocrinology

Background:

• Pancreatic islets are crucial for insulin secretion.
• Glucose metabolism plays a key role in regulating insulin release.
• Understanding glucose utilization pathways in islets is essential for diabetes research.

Purpose of the Study:

• To investigate glucose oxidation, lactate output, and glucose 6-phosphate levels in mouse pancreatic islets.
• To determine the effects of various substances on glucose metabolism and insulin release pathways.
• To elucidate the role of glucose phosphorylation in glucose-stimulated insulin secretion.

Main Methods:

• Measurement of glucose oxidation via (14)CO(2) formation from [U-(14)C]glucose.
• Assessment of lactate production and intracellular glucose 6-phosphate concentrations.
• In vitro incubation of mouse pancreatic islets with varying glucose concentrations and inhibitors.

Main Results:

• Glucose oxidation rate was highly dependent on extracellular glucose, particularly between 1-2 mg/ml.
• Mannose and fructose were oxidized but less efficiently than glucose, with poor interconversion.
• Inhibitors like mannoheptulose and glucosamine affected glucose phosphorylation and lactate output, while tolbutamide stimulated lactate production.

Conclusions:

• Glucose utilization in mouse islets may be limited by glucose phosphorylation rate.
• Mannose metabolism shows poor equilibration between fructose 6-phosphate and glucose 6-phosphate.
• Glucose metabolism, influenced by glucose phosphorylation, likely mediates glucose-stimulated insulin release.