SPECTRAL-ANALYSIS OF ARTERIAL-PRESSURE LABILITY IN RATS WITH SINOAORTIC DEAFFERENTATION

Traditionally, the standard deviation (SD) of the mean arterial pressu re (AP) has been used as an index for the AP lability produced by inte rruption of baroreceptor afferents. Although a useful measure of varia nce about the mean, the SD does not provide any information about the temporal characteristics of this variability. We employed two differen t spectral analytic techniques to characterize AP waveforms in rats wi th sinoaortic deafferentation (SAD) and in sham-operated (Sham) rats t o determine if the AP waveform in SAD animals was qualitatively and/or quantitatively different from that of Sham animals. The SAD and Sham animals exhibited qualitatively different spectral profiles, suggestin g that lability of AP in SAD animals is not simply an exaggeration of normal fluctuations. In addition, a low-frequency (0.3-0.5 Hz) spectra l peak was found in Sham hut not SAD animals, suggesting that it is as sociated with the baroreflex. Finally, we observed in both normal rats and rats without intact baroreceptors that the spectral components of AP are not static but rather vary continuously across time.