Glucose and lactic acid trends in suspension cultures of two established mammalian cell strains in chemically defined media

Abstract

SummaryIn replicated 30 to a m 1 suspension cultures of rapidly proliferating monkey kidney cells of a comparatively fragile strain, the rates of glucose utilization and lactic acid accumulation averaged about -100 micrograms and 110 micrograms per 106 cells per day respectively, with average molar La/G1 ratios of 0.48. These two rates of glucose utilization and lactic acid accumulation were about 4 x and 1Ox as high as the corresponding rates in comparable cultures of the hardier strain 2071-L mouse fibroblasts under the same conditions, with average molar La/G1 ratios of 0.16. In comparable but nonproliferating suspension cultures of the same strain of monkey kidney cells, during about 3 weeks the rates were extremely high, with about 710 micrograms glucose utilized and 445 micrograms lactic acid accumulated per 106 cells per day, with average molar La/G1 ratios of 1.37. The rates of glucose uptake and lactic acid accumulation were higher in the nonproliferating cultures aerated with 570 CO, in air than in those aerated with 10% CO, in air. This difference was aasociated with pH, which was higher in the former group.It was concluded that with this fragile strain of monkey kidney cells ( 1 ) in nonproliferating cultures the cells were metabolizing actively but with a marked tendency to higher La/Gl ratios, ( 2 ) in the proliferating cultures the high rates of glucose utilization and lactic acid accumulation were definitely not directly correlated with the rate of growth, and (3) in none of the cultures was the amount of glucose remaining in the fluid at fluid changes so low as to have been a limiting factor.Information in the literature concerning glucose utilization and lactic acid production by cells in vitro is voluminous and in some respects contradictory. 430 JAY C. BRYANTIn the present study the rates were unexpectedly high for the monkey kidney cells, particularly those in the otherwise apparently inactive nonproliferating cultures. The data seem to be unique, in that an established strain of cells in chemically defined medium in suspension cultures has been characterized for these metabolic parameters in both proliferating cultures and in equivalent nonproliferating cultures under directly comparable conditions. The concept waa developed that since these monkey kidney cells are obviously more fragile than the other cells examined, the complex physical stresses imposed upon these cells in agitated cultures can be modified and lessened in order to permit growth. Lessening of such mechanical stress waa brought about in several ways, of which only the smaller flask size seemed to be a t least partly effective. Increasing eit,her the concentration or the viscosity type of Methocel waa not effective.