Baroreflex stabilization of the double (pressure-rate) product at 0.05 Hz in conscious rabbits.
The product of heart rate (HR) and systolic blood pressure (SBP), the double product (DP), is an indirect index of cardiac oxygen consumption. We used spectral analysis to test the hypothesis that baroreflex adjustments of HR stabilize the DP during spontaneous variations in SBP. SBP and HR were recorded by telemetry in five male conscious rabbits. HR and SBP power spectra each exhibited a low frequency peak at approximately 0.05 Hz that was associated with high (>0.5) spectral coherence and a positive phase relationship between SBP and HR (SBP leading). A prominent peak was absent in the spectra of their product, suggesting that SBP and HR interacted to reduce DP variability in this frequency region. In contrast, a prominent 0.05-Hz peak was present in the power spectrum of calculated surrogates of the DP in which reflex interactions between HR and SBP had been removed. Our results suggest that baroreflex adjustments of HR stabilize the DP during spontaneous low-frequency variations in SBP in conscious rabbits.
Van Vliet
Bruce N
BN
Faculty of Medicine, Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3V6. vanvliet@mun.ca
Belforti
Francesca
F
Montani
Jean-Pierre
JP
D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D003243:Consciousness / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics; D008297:Male; D011817:Rabbits; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013599:Systole