Phosphatase Activity in H om ogena tes from Normal and Poliovirus Infected Tissue Cultures

Concentrated suspensions of equal numbers of normal and poliovirus infected cells at 37 °C were sampled periodically. Cell homogenates prepared from these samples were analyzed for total nitrogen content and for total ATP-ase, alkaline phosphatase, and glucose-6-phosphatase activity. The homogenates prepared from equal numbers of virus infected cells showed a logarithmic de­ crease in nitrogen with respect to time over the period from four to twelve hours after infection. No additional loss in nitrogen occurred during the following twelve hours. Such nitrogen losses were associated with a decrease in the activity of the three enzymes. In the case of ATP-ase this decrease between the four and twelve hour period was linear with respect to time. The activity of this enzyme remained constant during the following twelve hours. The nitrogen content and activity of the three enzymes in homogenates prepared from normal cell suspensions did not increase over the sampling interval. The large amount of bicarbonate required to maintain the ph of the culture under these conditions produced an unfavorable environment for the cells. This was confirmed by the finding that normal cells placed initially in tissue culture medium, at standard pH , containing excessive amounts of bicarbonate showed no. metabolic activity. Such cells exhibited a marked reduction in total nitrogen and in the activity of the three enzymes over a sampling interval of twelve hours. When normal cells were placed in the tissue culture medium, at standard pH , con­ taining such excessive concentrations of bicarbonate, and immediately infected with poliovirus, a delay in the synthesis of, and a marked reduction in final titer of the virus resulted from that found under control conditions.