Background Sinoaortic denervation (SAD) and sepsis are known to disrupt autonomic nervous system (ANS) regulation of cardiovascular (CV) function. However, the possible similarities between the dysregulation induced by them are unknown.
Objective This study aimed to carry out a preliminary comparison of the effects on ANS due to SAD and cecal ligation and puncture-induced sepsis in Wistar rats.
Methods Invasive pressure was collected via a catheter inserted in the femoral artery of rats randomly assigned to three experimental groups (n=3): SAD, Sepsis, and Sham. Diastolic and systolic arterial pressure (DAP, SAP) and heart period (HP) time series were derived from the pressure waveform. ANS was probed by computing a) sample and approximate entropy to investigate signal complexity; b) frequency power spectra to obtain classical indices of CV variability (VLF, LF, HF power density). Baroreflex sensitivity (BRS) was estimated using bivariate autoregressive models. Group comparisons were conducted using one-way ANOVA with post-hoc Tukey test.
Results Both sample and approximate entropies pointed to greater unpredictability of DAP and HP in Sham and Sepsis, while SAD animals exhibited greater complexity in SAP, with opposite trends compared to the other groups (p < 0.05). Significant differences (p < 0.05) were found in the VLF and HF spectral bands of SAP and DAP in SAD animals. The LF component of BRS in the SAD group exhibited high intragroup variability, while sepsis showed a suppression of the response (p < 0.05).
Conclusion This preliminary study showed that SAD and sepsis distinctly and markedly affect ANS control of CV function, with SAD increasing CV complexity and sepsis resulting in the inhibition of baroreflex responses. Combining nonlinear and linear approaches to CV variability is a promising approach to shed further light on the pathophysiological basis of ANS dysregulation occurring in sepsis and acute illness.