Power spectrum analysis of cardiovascular variability in anaesthetised SHR and WKY rats

A comparative analysis of beat-to-beat heart rate variability (HRV) and arterial blood pressure variability (BPV) was performed in a group of four spontaneous hypertensive rats (SHR) vs. A control group of four Wistar-Kyoto (WKY) rats. All them were anaesthetised with sodium pentobarbital. HRV and BPV power spectra were computed by a parametric method based on autoregressive models (AR). The authors' HRV spectral analysis showed a high frequency (HF) component whose amplitude was lower (46%, p<0.05) in the SHR group compared to the WKY group. This was interpreted in terms of a reduced cardiac vagal activity in the SHR. A 122% (p<0.05) increase in the low frequency (LF) component of the BPV spectra in the SHR group suggests the presence of an enhanced vascular sympathetic tone.