The effects of dietary deficiencies of magnesium and potassium on the growth and chemistry of transplanted tumours and host tissues in the rat

1. 1. Weanling rats on control diet or a diet deficient in magnesium and/or potassium for 1–3 weeks were transplanted with Yoshida or Walker tumours. Restricted intakes were given to prevent nutritional differences between the groups. Cation depletion was assessed from plasma and muscle concentrations. 2. 2. Organ weights and tissue biochemistry showed that metabolic differences between control and cation deficient rats were due predominantly to cation deficiency and the tumour growth rather than other nutritional deficiencies. 3. 3. Reduction in tumour size occurred in Mg deficiency (up to 40%), K deficiency ( 30–60%) and in combined deficiency ( 45–85%). Tumour size showed the best correlation with the combined concentration of plasma Mg and K or muscle-K. 4. 4. Significant reduction in tumour K was observed only in marked combined deficiency. 5. 5. Correlation between Mg and K was found in tumour but not in muscle. 6. 6. Dietary depletion of both Mg and K cause the removal of K from tissues and may affect the replication and survival of tumour cells by inhibiting metabolic activity and causing the loss of intracellular K.