[Circadian fluctuations in the indices of the cardiac intervalogram and their relation to the characteristics of circadian mobility in rats].

Mathematical analysis of the heart rate variability enables one to determine the activity of the sympathetic nervous system at different time of day in rats. A correlation was found between the cardiac intervalogram parameters and the dynamics of rats' circadian motility. Intensification of locomotor activity by day was accompanied by an increase in the sympathetic tone.

[The effect of caffeine on the cardiac intervalogram indices depending on the ovarian cycle phase in women].

Caffeine (0.1 g) was shown to increase the variability of the heart rate (parameters of the cardiointervalogram) in 10 healthy women irrespective of their vegetative and hormonal status. The combined use of caffeine and cardiointervalogram reveals "risk phases" in the ovarian cycle of women, accompanied by tension of the adaptive mechanisms.

[The cardiointervalogram indices of rats in relation to sex and estrous cycle phase].

Male rats manifested a lesser heart rate variability than the female animals. Optimal shifts of the heart rate mathematical parameters occurred in the dioestrus II and oestrus as compared with other phases of the ovarian cycle. Ovariectomy stabilised the heart activity, the effect being eliminated by administrations of estradiol.