Cori cycle contribution to plasma glucose appearance in man

Area of Science:

• Biochemistry
• Human Physiology
• Metabolic Research

Background:

• The Cori cycle recycles lactate to glucose in the liver.
• Previous estimates of Cori cycle contribution to glucose metabolism were based on labeled glucose infusions and liver balance studies.
• These methods yielded an estimate of ~15% for Cori cycle's role in plasma glucose appearance.

Purpose of the Study:

• To re-evaluate the contribution of the Cori cycle to human glucose metabolism.
• To address the overestimation of precursor specific activity in prior calculations.
• To refine the understanding of glucose turnover dynamics.

Main Methods:

• Utilized previously published human data on substrate utilization.
• Applied glucose turnover kinetics analysis.
• Derived an empirical correction factor (2.7) for label dilution in precursor pools.

Main Results:

• Identified overestimation in specific activity of gluconeogenic precursors.
• Developed a correction factor of 2.7 to account for label dilution.
• Demonstrated that the Cori cycle's contribution to glucose turnover is significantly underestimated by previous methods.

Conclusions:

• Previous estimates of Cori cycle activity (~15%) require substantial upward revision.
• Label dilution in gluconeogenic precursors significantly impacts calculations of glucose recycling.
• Accurate quantification of the Cori cycle is crucial for understanding human glucose homeostasis.