Circadian variations in 32P uptake of a DMBA-induced mammary tumour and Walker carcinosarcoma in rats

Abstract

Summary.-The 32p uptake in a mammary tumour induced by DMBA and in the Walker 256 carcinosarcoma was measured by external GM-tubes. The uptake was significantly higher than in the skin. During exposure to a synchronized light regime a circadian variation was present in the 32p uptake of the hormonedependent DMBA-induced tumour. The maximal 32p uptake was in the dark period, in which the highest temperature in the tumour has also been found (M0ller and Bojsen, 1975). In the hormone-independent Walker 256 carcinosarcoma there was no periodicity in 32p uptake. No variation in 32p uptake was registered in the skin of normal controls or in tumour-bearing rats.

Biodistribution of 131I in mice is influenced by circadian variations

“…The number of studies on diurnal effects related to radiopharmaceuticals are even fewer. A handful of studies from the 50 s, 60 s and 70 s have observed circadian variations in 32 P (orthophosphate) uptake in mammary tumors 11 , 33 – 35 . The intention then was to use 32 P as a marker for mitotic activity in the tumors and thereby be able to choose a time-point for external radiotherapy when tumor is more radiosensitive.…”