Abstract: | The concentration of total, free and bound cholesterol in the blood serum of 13 intact Chinchilla male rabbits was determined in two four-month experiments carried out in 1973-1974 and in 1984-1985 during a "minimum" phase of an 11-year solar activity cycle. A hierarchy of ten cholesterol biorhythms and solar activity rhythms were singled out on a computer, using an original algorithm, in the individual changes in cholesterol concentration in each rabbit and in changes in seven environmental indexes. A statistical stability of the frequency and phase of low-frequency cholesterol biorhythms and solar activity rhythms has been established within an 11-year period, the fluctuation amplitude of the indexes studied being, on the contrary, statistically unstable. |