Ciclo de Cori [ciclo del ácido láctico o lactado] | Metabolismo

Understanding the Cori Cycle: Lactate Metabolism

Overview of the Cori Cycle

• The Cori cycle is a metabolic pathway that transports lactate produced in skeletal muscle to the liver for conversion into glucose, which can then be utilized by muscles again.

• Lactate is formed during vigorous exercise through lactic fermentation, where pyruvate is converted to lactate by the enzyme lactate dehydrogenase, which requires NADH.

Lactate Production and Accumulation

• Skeletal muscle produces lactate under high energy demand or fasting conditions, utilizing glycogen reserves that convert to glucose 6-phosphate.

• Glucose 6-phosphate enters glycolysis to form pyruvate; due to energy demands, pyruvate is converted into lactate via fermentation.

Recycling of Lactate

• Lactate cannot accumulate in blood or tissues as it leads to acidosis, necessitating its recycling primarily in the liver and kidneys.

• In the liver, lactate is converted back into pyruvate without requiring NADH but rather using oxidized forms.

Gluconeogenesis Process

• Pyruvate serves as a substrate for gluconeogenesis—the formation of glucose from non-carbohydrate sources. Two pyruvates (3 carbons each) are needed to produce one glucose molecule (6 carbons).

• Once synthesized, glucose travels through the bloodstream back to skeletal muscle where it converts back into glucose 6-phosphate for further processing or storage as glycogen.

Key Takeaways on Energy Utilization

• The cycle continues as long as muscles require energy; excess glucose 6-phosphate can be stored as glycogen when not immediately needed.