From the Guidelines
The first result of anaerobic tissue metabolism is A. lactic acid. When tissues lack sufficient oxygen to perform aerobic metabolism, cells switch to anaerobic glycolysis to continue producing ATP for energy. During this process, glucose is broken down without oxygen, and pyruvate is converted to lactic acid instead of entering the Krebs cycle. This lactic acid accumulation causes the burning sensation felt in muscles during intense exercise when oxygen demand exceeds supply. The body later converts this lactic acid back to glucose in the liver through the Cori cycle when oxygen becomes available again. Unlike aerobic metabolism which produces CO2 and water as end products, anaerobic metabolism's primary immediate product is lactic acid, which serves as a temporary energy solution that allows tissues to continue functioning briefly during oxygen deficiency. Some studies have shown the importance of lactic acid in determining the severity of tissue hypoperfusion and haemorrhagic shock 1. For example, serum lactate has been used as a diagnostic parameter and prognostic marker of haemorrhagic shock since the 1960s, and changes in lactate concentrations provide an early and objective evaluation of a patient’s response to therapy 1. Additionally, the amount of lactate produced by anaerobic glycolysis is an indirect marker of oxygen debt, tissue hypoperfusion and the severity of haemorrhagic shock 1. In contrast, other options such as CO2 and CO are not the primary immediate products of anaerobic tissue metabolism. Key points to consider include:
- Lactic acid is the primary product of anaerobic glycolysis
- Lactic acid accumulation causes tissue acidosis and hypoperfusion
- Serum lactate is a diagnostic parameter and prognostic marker of haemorrhagic shock
- Changes in lactate concentrations provide an early and objective evaluation of a patient’s response to therapy The most recent and highest quality study on this topic is from 2013, which highlights the importance of lactate in determining the severity of tissue hypoperfusion and haemorrhagic shock 1.
From the Research
First Result to Anaerobic Tissue Metabolism
- The first result to anaerobic tissue metabolism is lactic acid, as stated in the study 2, which explains that lactic acid is generated as the end product of anaerobic metabolism of glucose.
- This is further supported by study 3, which discusses the lactate paradigm and its shift, indicating that lactate is an important intermediate in the process of wound repair and regeneration.
- Study 4 also explains that lactate production retards, not causes, acidosis, and that increased lactate production coincides with cellular acidosis, making it a good indirect marker for cell metabolic conditions that induce metabolic acidosis.
- Additionally, study 5 provides an overview of the biochemical and metabolic background required to understand the different pathophysiological mechanisms that may lead to the development of L-lactic acidosis, which is associated with increased production or decreased removal of L-lactic acid.
- Study 6 also summarizes emerging evidence that lactate serves as a major circulating carbohydrate fuel, providing mammalian cells with both a convenient source and sink for three-carbon compounds, and enabling the uncoupling of carbohydrate-driven mitochondrial energy generation from glycolysis.