The aim of this study was to detect synchronization between blood pressure variability (BPV) and the respiratory rhythm in healthy rats and rats with experimentally induced colitis during noxious (pain) stimulation. To this end, we used synchronization metrics based on instantaneous frequencies and phases estimated via the synchrosqueezed wavelet transform. We found that noxious stimulation promotes the emergence of synchronization between BPV and respiration. The adjustment of the BPV frequency to the respiratory frequency, followed by phase locking, indicates that the respiratory rhythm controls BPV prior to the onset of synchronization. The pathological condition associated with experimental colitis correlates with a reduction in the duration of phase synchronization.

Keywords: arterial blood pressure; respiratory activity; wavelet decomposition