Temporal analysis of the spontaneous baroreceptor reflex during acute and chronic shaker stress in freely moving rats

Radiotelemetred male Wistar conscious rats were exposed to acute and chronic shaker stress and the spontaneous baroreceptor reflex (sBRR) functioning was evaluated using the method of sequences. Baroreflex sensitivity (BRS) is calculated using traditional, local and global approach. Contour coverage area (CCA, area embedding the sequence points in SBP-PI plain) with coordinates of baricentre (mass center of CCA) were proposed to evaluate the range and the set point of sBRR. Acute shaker stress increased vigilance and HR, induced no changes in BRS and decreased the range and the set point of sBRR, which was displaced towards lower PI and higher SBP values. Chronic shaker stress reduced only sBRR range. In the post-stress period of acute and chronic shaker stress shortening of baroreflex sequences and SBP ramps, SBP and PI increments and swings were noted, indicating that the BRR functioning is shifted toward faster BP changes.