[Circadian rhythm of adenosine triphosphatase activity and 32P content in Pliss lymphosarcoma]

Within a daily period maximal activity of ATPases and content of 32P in Pliss lymphosarcoma tissue was found in the samples taken at 15 or 21 p.m. and 3 a.m. The radioactivity in the tumor was minimal between 9 and 12 a.m. and 18 or 24 p.m. The alterations in Mg2+-ATPase activity in their magnitude and circadian rhythm coincided completely with the daily variations in content of radiophosphorus. Activities of Na+, K+- and HCO(3-)-ATPases exhibited maximal values at 15 p.m. and, especially between 3 and 6 a.m., i.e. these alterations were of two-peak shape without the peak at 21 p.m.