Objective: To develop and use a closed chamber to study the metabolism of isolated disc cells under controlled conditions such as reduced pH.

Design: Disc cells were incubated in the chamber for four hours, while embedded electrodes measured pH and pO2. A port allowed sampling.

Subjects: Nucleus pulposus cells were isolated from the coccygeal discs of 33 steers (18–24 months old), within three hours of slaughter.

Outcome measures: Metabolic rates were calculated from concentration changes. Cell viability was assesed on completion.

Results: At pH 7.4, metabolic rates were similar to those measured in tissue [1, 2] with lactic acid production and oxygen consumption rates of 157 and 12 nmol/million cells/hour respectively, and a 1: 2 ratio of glucose consumption: lactic acid production. Lactic acid production and oxygen consumption fell with extracellular pH, to 89 and 65 nmol/million cells/hour (lactate) and 8 and 5 nmol/million cells/hour (oxygen), at pH 6.7 and pH 6.2 respectively.

Conclusions: These results show a fall in lactic acid production and oxygen consumption with extracellular acid-ification. There is a complex interplay between different components of the nutritional environment. Investigating these in combination should give valuable information about disc cell metabolism, as changes can affect nutrient availability and hence cellular activity, viability, and matrix production rates.