Blood pressure and heart rate variability in conscious rats before and after autonomic blockade: evaluation by wide-band spectral analysis

The aim of this work was to study the influences of the autonomic nervous system on blood pressure and heart rate spontaneous variability by separate blockades of sympathetic and parasympathetic efferent activity. In normotensive rats the effects of sympathetic and parasympathetic blockade were evaluated making use of a specific wide-band spectral and coherence analysis of systolic blood pressure, SBP, and pulse interval, PI. After sympathectomy, PI spectral components were significantly reduced between 0.012 and 0.22 Hz while SBP components were reduced between 0.08 and 1.53 Hz but increased between 0.0024 and 0.039 Hz; sympathectomy also increased the coherence modulus below 0.02 Hz. Parasympathetic blockade decreased all the PI spectral components, the SBP respiratory fluctuations and uncoupled SBP and PI at the respiratory frequency