Influence of pH and serum on the effectivity of antineoplastic agents in vitro.

pH and serum are important factors in cell cultures in vitro. Only 47.4% of 3H-uridine incorporation were measured in cells incubated with medium pH 6.8 in comparison to control cultures (mesothelioma cells, 30th passage; pH 7.4; 3H-uridine incorporation 100%). Changes of pH can also influence the cytotoxic activity of 5-Fluorouracil (2.9 X 10(-4) M). We measured greater inhibition of 3H-uridine incorporation with medium pH 6.8 (79.9%) in comparison to medium pH 7.4 (54.0%). Influence of serum (10%) on the cytotoxicity of Viknblastine (7.4 X 10(-9)M) were measured. Foetal calf serum (FS 883) and calf serum (KS 132) showed similar effects on the inhibition of 3H-thymidine incorporation, 78.1% and 87.4% respectively. But calf serum (KS 199) supplemented medium produced only 40.6% inhibition of disintegrations/microgram DNA. The possible factors (pH, osmotic activity, protein distribution) of these sera will be discussed.