Circadian rhythms in polyamine excretion by rats bearing an immunocytoma.

Large-amplitude circadian rhythms were observed in the urinary excretion of polyamines by rats bearing an immunocytoma. Control animals excreted polyamines at a lower rate but also with marked circadian variation. In confirmation of earlier observations, light-chain excretion by the tumor-bearing rats also exhibited a circadian rhythm, superimposed on an increasing trend. The potential of these rhythms as markers for the chronotherapy of cancer is noted.