Peculiarities of heart rhythm variability in narcotized and immobilized wakeful rats during blockade of calcium channels.

In narcotized rats, verapamil and cinnarizine modified some heart rate variability (HRV) indices and heart rate (HR) indicating up-regulation of parasympathetic tone in contrast to nifedipine that elevated activity of sympathetic subdivision of ANS producing no influence on HR. In wakeful stressed rats, the time-domain and geometric analysis established that verapamil decreased HR and up-regulated sympathetic tone; nifedipine elevated sympathetic tone and produced no effect on HR, while cinnarizine enhanced parasympathetic tone without any effect on HR. Spectrum analysis of HRV revealed probable activation of some other neurohumoral mechanisms by the employed calcium blockers.