5 - Cori Cycle

What is the Cori Cycle?

The Cori Cycle is the metabolic pathway in which lactate produced by anaerobic glycolysis in muscle is transported to the liver, converted back to glucose, and returned to the muscle.

What is the function of the Cori Cycle?

To remove lactate from muscle (preventing acidosis) and to recycle it into glucose in the liver, maintaining blood glucose and enabling continued ATP production in muscle during anaerobic activity.

How does the Cori Cycle accomplish its function?

• Muscle: Glucose → Pyruvate → Lactate (via anaerobic glycolysis)

• Lactate → Liver via blood

• Liver: Lactate → Pyruvate → Glucose (via gluconeogenesis)

• Glucose returns to muscle via blood

Can the Cori Cycle function indefinitely?

No. It requires ATP input in the liver for gluconeogenesis. Eventually, energy sources (like ATP, GTP, NADH) may become limiting.

How is the Cori Cycle integrated with allosteric and hormonal control in the liver?

• Allosteric: Pyruvate carboxylase is activated by acetyl-CoA; fructose-1,6-bisphosphatase is inhibited by AMP, activated by citrate

• Hormonal: Glucagon promotes gluconeogenesis and glycogenolysis; insulin suppresses both

How is the Cori Cycle integrated with allosteric and hormonal control in skeletal muscle?

• Allosteric: Glycogen phosphorylase activated by AMP, inhibited by ATP

• Hormonal: Epinephrine stimulates glycogenolysis and glycolysis

• Muscle lacks glucose-6-phosphatase, so glucose is retained for energy