Effects of cell density and glucose and glutamine levels on the respiration rates of hybridoma cells

Abstract

The effects of cell density as well as the concentration levels of glucose and glutamine on the specific respiration rate of a hybridoma cell line were investigated. The experimental oxygen consumption rate was found to be constant over a wide range of dissolved oxygen levels if the suspension medium contained glutamine. In glutamine‐free medium, however, the rate of oxygen consumption decreased slowly with time.In a stationary flask batch culture, the specific respiration rate decreased from about 7 to 2.9 μmol/min per 10⁹ cells as the cell density increased exponentially from 1 × 10⁵ to 1.2 × 10⁶/mL. To isolate the effect of cell density, cells were re suspended in fresh culture medium so that nutrient concentrations were the same for all experiments. The specific respiration rate decreased with increasing cell density in the same manner as in the stationary flask culture, falling from 8 to 4 μmol/min per 10⁹ cells as the cell density increased from 10⁵ to 10⁶ cells/mL, then declining to 2 μmol/min per 10⁹ cells when the cell density reached 10⁷ cells/mL.Cells suspended in Hanks balanced sale solution (HBSS) were used to elucidate the effect of glucose and glutamine levels on respiration. The addition of glucose in concentrations of 0.25, 0.50, and 0.75 g/L had no observable effect on the specific oxygen uptake rate; however, a glucose concentration of 1 g/L reduced the uptake rate by 22%. Glutamine in a concentration of 0.30 g/L increased the specific respiration rate in HBSS containing 0 and 1 g/L glucose by approximately 13%.