The baroreflex accounts for one-half of the low-frequency power spectral density of mean arterial pressure and for the coherence between MAP and HR oscillations in the low-frequency band in rats.
Does the baroreflex modulate the spectral characteristics of blood pressure and heart rate variabilities in rats?
The baroreflex accounts for approximately half of the low-frequency power spectral density of mean arterial pressure and the coherence between MAP and HR oscillations in rats.
The role of the baroreflex in the spectral characteristics of mean arterial pressure (MAP) and heart rate (HR) was investigated in 12 control rats and 9 rats with chronic sinoaortic baroreceptor denervation (SAD) during 1) basal conditions and 2) ganglionic blockade with chlorisondamine and restoration of the basal MAP level. In SAD rats, power spectral density of MAP, estimated by a fast Fourier transform, was reduced in the low-frequency (LF, 0.27- to 0.74-Hz) band. Ganglionic blockade highly decreased LF power spectral density of MAP in control rats. No relationship was found between the MAP response to chlorisondamine, taken as an index of the sympathetic vasomotor tone, and the basal LF power spectral density. Transfer function analysis between MAP and HR showed that, in control rats, coherence was high for frequencies surrounding the LF and high-frequency peaks. In SAD rats, coherence was abolished in the LF band but maintained in the high-frequency band. In conclusion, approximately 80% of the LF power spectral density of MAP depends on the sympathetic nervous system activity, and the baroreflex accounts for one-half of this power and for the coherence between MAP and HR oscillations in the LF band.
Cerutti et al. (1994) studied this question. Chronic sinoaortic baroreceptor denervation (SAD) and ganglionic blockade vs. Control rats was evaluated on Low-frequency power spectral density of mean arterial pressure and coherence between MAP and HR. The baroreflex accounts for one-half of the low-frequency power spectral density of mean arterial pressure and for the coherence between MAP and HR oscillations in the low-frequency band in rats.