[Afobazole effect on heart rate variability in rats with different behaviors in the "open field" test].

The course of cardiovascular diseases is known to depend upon vegetative nervous system condition. The heart rate variability is the quantitative indicator of vegetative nervous system activity. The emotional stress reaction in rats tested in the "open field" was assessed by measuring the heart rate variability, which allowed the chronotropic cardiac function to be studied in detail and showed which part of the vegetative system (either sympathetic or parasympathetic) prevails in animals with different phenotypes of the emotional stress reaction. In rats demonstrating different behaviors in the "open field" test, changes in the heart rate variability were examined under conditions of the emotional stress response development and the treatment with non-benzodiazepine anxiolytic afobazole. It was established that the sympathetic nervous system tone prevails in stress-resistant rats, whereas in non-resistant animals, the parasympathetic system is predominating. In non-resistant rats exposed to stress, the heart rate variability decreased due to reduced power of very low frequencies, in contrast to stress-resistant animals, which showed increased power of very low frequencies. Afobazole was found to increase the heart rate variability in both animal groups. In non-resistant rats, afobazole also raised the vagus tone.