Oxygen consumption of equine articular chondrocytes: Influence of applied oxygen tension and glucose concentration during culture.

This research aims to understand how horse cartilage cells (or equine articular chondrocytes) consume oxygen and react to periods of anoxia (oxygen deprivation) and subsequent re-oxygenation. Additionally, the impact of different oxygen and glucose levels in the culture medium on these cells is examined.

Study Design and Procedures

• The scientists cultured equine articular chondrocytes (cartilage cells) under two different oxygen conditions—5% and 21%—and with three varying glucose concentrations (0, 1.0 or 4.5g/L) in the culture medium.
• They applied an anoxia (oxygen deprivation) period of 25 minutes to the cultures and then used oxymetry, a process to measure the rate of oxygen consumption, to determine how the chondrocytes respond before and after this period.
• They also measured the glucose consumption and lactate release of the cells at the end of the re-oxygenation phase.

Oxygen Consumption Findings

• The equine chondrocytes showed a minimal rate of oxygen consumption, which remained largely unchanged throughout the period of oxygen deprivation.
• This demonstrated the surprising resilience of these cells to variations in oxygen supply – they appeared functionally indifferent to anoxia and re-oxygenation, despite possessing a functioning mitochondrial respiratory chain (responsible for oxygen-dependent energy production).

Glucose Metabolism and Lactate Release

• Irrespective of the oxygen tension (level of oxygen supply), the cells consumed about 30% of the available glucose in the medium. This means that cells cultured at a higher glucose concentration (4.5g/L) ended up consuming more glucose.
• The amount of lactate (a byproduct of glucose metabolism) released by the cells was unaffected by changes in oxygen supply. However, cells cultured at a higher glucose concentration tended to release less lactate.

Conclusion

• In conclusion, the study revealed that equine chondrocytes have a low oxygen consumption rate and are resilient to periods of oxygen deprivation and re-oxygenation.
• The researchers also found that the metabolism of these cells was affected by excessive oxygen and glucose supply, contrary to the initial presumption that higher oxygen and glucose levels in the culture medium would increase oxygen consumption and glucose metabolism.