The relation between glucose utilization, lactic acid production and utilization and the growth cycle of L strain fibroblasts

Abstract

1. 1. Glucose and lactate metabolism of L strain fibroblasts growing in an agitated suspension was correlated with the growth phase of the culture and with changes in the average cell volume and pH changes in the medium.2. 2. In agreement with previous work, it was found that the rate of glucose uptake and lactate production was most rapid during the first part of the logarithmic growth period. It was found, however, that lactate was taken up by the cells when glucose was still present in relatively high concentrations. During the last half of the logarithmic growth period, lactate was rapidly taken up and the rate of glucose uptake was low. Lactate was found to accumulate in the medium for the second time as the cultures entered the plateau phase of growth. Later in the plateau phase, lactate was reduced to very low values and glucose was exhausted from the medium after 192 hrs.3. 3. From the observation that the pH decreased while lactate decreased in concentration it was concluded that other factors causing pH depression must have been functioning at that time.4. 4. A calculation of the rate of cell carbohydrate metabolism indicated that there was no constant relation between the rate of carbohydrate uptake per cell and the rate of mitosis during progressive intervals of the growth cycle. It is hypothesized that the rate of cell carbohydrate metabolism is directly related to average cell volume.