1. Folate deficiency is reported in association with certain malignant tumours, and it has been suggested that this arises from increased folate turnover and catabolism in such circumstances.
2. Using an experimental animal model to determine the rate of catabolism of [3H]pteroylglutamate (folic acid) by the quantitative estimation of the two urinary catabolites p-[3H]aminobenzoylglutamate and [3H]acetamidobenzoylglutamate, we have measured the rate of folate catabolism in mice with ascitic tumours.
3. There was a significant increase in the rate of catabolism in the mice with tumours compared with controls over a 10 day period. This was associated with the accumulation of ascitic fluid and an increase in the number of tumour cells in the treated animals.
4. The increase in catabolism appeared to be due to increased cell turnover of the tumour rather than an increase in cell mass, as the increase in mass of the tumour was negligible.