Influence of serum and poliovirus infection on the transport and accumulation of AIB in HeLa cells

The kinetics of active transport of the model amino acid AIB (aminoisobutyric acid) into HeLa cells were analysed. Serum withdrawal from cell-culture medium prior to transport assay strongly lowers the influx and steady-state distribution of AIB. Readdition of serum restores the rate of influx within 30 min, while the capacity to concentrate AIB is only partially reestablished. These changes are due to alterations in the activity of system A. In the time-course of poliovirus infection the initial rate of AIB transport shows two distinct changes. Early in the infection there is an increase in influx, followed by a strong decrease later in infection. These alterations are also attributed to transport system A.