Intensity of K Decay Fluctuations an Indicator of an Environmental Factor Determining Infradian Rhythms of Mouse Motor Activity, Circulating Cortisol in Rabbits, and Proliferation of L-929 Cultured Cells.

The multi-day dynamics of the intensity of K decay fluctuations was compared with motor activity of laboratory mice, circulating cortisol in rabbits, and proliferation of fibroblast-like cultured cells L-929. A positive correlation was established between the intensity of decay fluctuations on the one hand, and total daily motor activity in mice and plasma cortisol level in rabbits, on the other hand. In addition, a negative correlation was observed between K decay fluctuations and proliferative activity of the cultured cells. Interestingly, these close correlations were observed not only against the background 4-day rhythm, but also in the time when any rhythmicity was absent. Thus, the intensity of K decay fluctuations is an indicator of a biotropic environmental factor that augments motor activity and raises the circulating cortisol in animals and down-regulates proliferation of cultured cells.