Peculiarities of Heart Rate Variability Changes in Random-Bred Male Rats during Transition into Anesthetic Sleep under Stimulation of Central Neurotransmitter Systems

General anesthesia with Nembutal (40 mg/kg) dramatically decreased the power of all waves of HRV spectrum in rats, especially in LF and VLF frequency bands, but the HR and respiration rate were little changed. At this, individual spectral peaks in HF range were observed at the same frequencies (1.3-1.5 Hz), which are characteristic of the wakeful state. Preliminary stimulation of noradrenergic system with maprotiline (10 mg/kg) increased the power of HF waves and elevated the respiratory rate in narcotized rats in comparison with the control values, although it did not shift the spectral peak at 1.5 Hz in frequency axis. Preliminary stimulation of cholinergic system with galantamine (2 mg/kg) somewhat decreased the power of HF waves and respiratory rate in narcotized rats (in comparison with the control values); additionally, it shifted HF peak to 1.1-1.4 Hz. Activation of serotonergic system with 5-hydroxytryptophan (50 mg/kg) and fluoxetine (3 mg/kg) decreased the HR, the power of HF waves, and respiratory rate in narcotized rats. It also shifted the spectral peak of HF waves to 0.9-0.95 Hz. Preliminary stimulation of dopaminergic system with L-DOPA (20 ml/kg) and amantadine (20 ml/kg) increased the power of VLF waves in narcotized rats in comparison with the control values. Numerous peaks appeared in HF (1.1-1.2 Hz) and VLF frequency bands. Generally, preliminary stimulation of serotonergic or dopaminergic systems markedly affects the neural activity under following general anesthesia: first aggravates the effect of anesthesia on vital centers in CNS, whereas second weakens the effect of anesthesia at the suprasegmental level of neural control.