[Uridine transport and phosphorylation in 3T3 and CHO cells depending on the culture growth conditions].

Uridine transport and phosphorylation were studied in cultured Swiss 3T3 CHO-K1 cells, differing in their growth characteristics. Uridine was shown to be transported to the cell with a high rate. With the 2 micronM uridine concentration in the medium, the stationary level of free uridine in cells is reached 10 seconds following incubation at 25 degrees, and the further uridine uptake is limited by phosphorylation.. The uridine transport to the cell does not depend on the DNA synthesis level and the growth phase of 3T3 and CHO-K1 cells. With the increase in culture density, the rate of uridine phosphorylation decreases in 3T3 cells being actually unchanged in CHO-K1 cells. With the equal cell density in both the cases, the phosphorylation rate in CHO-K1 cells is by several times higher than that in 3T3 cells. A positive correlation between uridine phosphorylation rate and DNA synthesis has been observed under various cultivation condition of CHO-K1 cells.