Muscle Fuel Utilization with Glycolysis Viewed Right Side Up

Area of Science:

• Metabolic physiology
• Cellular biology
• Exercise physiology

Background:

• Lactate is continuously produced in aerobic conditions by various cells and tissues.
• Lactate serves multiple roles including energy substrate, gluconeogenic precursor, and signaling molecule.
• Lactate shuttles (cell-cell, intracellular, astrocyte-neuron, peroxisomal, cytosolic-mitochondrial) have been previously identified.

Purpose of the Study:

• To elucidate the role of lactate in whole-body metabolism.
• To describe the newly discovered postprandial lactate shuttle (PLS).
• To understand carbohydrate carbon flux from dietary intake to tissue utilization.

Main Methods:

• Review of contemporary studies on muscle, tissue, and whole-body metabolism.
• Analysis of findings from exercise physiology research.
• Integration of recent discoveries concerning the postprandial lactate shuttle.

Main Results:

• Lactate production is a continuous process under aerobic conditions.
• The PLS involves two phases: enteric (gut lactate production) and systemic (hepatic and tissue metabolism).
• Carbohydrate carbon flux begins in the gut and concludes in muscles, with lactate playing a pivotal role.

Conclusions:

• Lactate is a crucial intermediary in carbohydrate metabolism.
• The PLS highlights the integrated nature of lactate's role in energy homeostasis.
• Understanding lactate dynamics is essential for comprehending whole-body metabolic processes.