Spectrum analysis of sympathetic nerve activity and blood pressure in conscious rats

Abstract

This study tests whether the power spectrum of blood pressure (BP) provides information toward the sympathovagal balance of BP control by comparing the BP (femoral arterial catheter) spectrum with the spectrum of the efferent sympathetic nerve activity (SNA, bipolar electrode around splanchnic nerve). A remarkable resemblance between both spectra was found. A high-frequency component (HF) linked to respiration and a slower fluctuation type between 0.15 and 0.6 Hz (LF) were identified. There was a large and significant coherence only in the HF range of the BP and SNA power spectrum (P < 0.01). The phase lag of SNA and BP was roughly 200 ms. The recordings were repeated during pharmacological blockade in nine Wistar-Kyoto rats (WKY) and nine spontaneously hypertensive rats (SHR). alpha 1-Adrenoceptor blockade (prazosin) reduced the proportional LF power of BP in both rat strains (WKY P < 0.01, SHR P < 0.05) in favor of HF (WKY P < 0.01, SHR P < 0.01). Parasympathetic blockade (methylscopolamine) had no effect on proportions of power. Similarly, there were no significant differences in the proportional HF and LF power spectra of WKY and SHR. These data provide direct evidence for a relationship between the BP and SNA power spectra; however, only the acute changes in the sympathetic tone changed the LF-HF relationship.

Effects of Bilateral Stellate Ganglion Block on Autonomic Cardiovascular Regulation

“…30 We did not assess the effects of bilateral SGB on MSNA; however, we measured the LF component of SBPV to estimate the peripheral sympathetic vasomotor tone because the LF component of SBPV is closely linked to vascular sympathetic outflow. [31][32][33][34][35] In contrast to previous reports, our data showed that the LF component of SBPV did not change after bilateral SGB. 29,30 Further investigation is needed to clarify the SGB-induced changes in peripheral sympathetic vasomotor tone.…”

Effects of Nonpeptide and Selective V1 and V2 Antagonists on Blood Pressure Short-Term Variability in Spontaneously Hypertensive Rats

“…It is interesting to note that in our experiments, hemorrhage that is usually associated with sympathetic activation (11,45,46,48) failed to modify LF-BP variability in SHR. In normotensive and young SHR, hemorrhage was found to increase 0.4-Hz oscillation (component of LF-BP oscillation) by inducing a positive feed-back response in the arterial baro-receptor reflex loop (14).…”

Immersion in CO2-rich water containing NaCl diminishes blood pressure fluctuation in anesthetized rats

“…The frequency ranges of VLF and LF roughly corresponded to those previously reported (Cerutti et al 1994;Janssen et al 1995;Japundzic et al 1990;Julien et al 1995;Persson et al 1992). All numerical data generated in the experiments are shown as means ± SEM.…”

“…The power spectral analysis of BP fluctuation might be a suitable way of detecting a subtle change in the cardiovascular system. Suppression of the sympathetic nerve activity by treatment with sympathetic β-blockers or sympathectomy reduces the low frequency (about 0.2 ~ 0.6 Hz) power of BP fluctuations (Cerutti et al 1991;Julien et al 1995;Persson et al 1992;Stauss et al 1995). Furthermore, the suppression of myogenic oscillation originating in the blood vessel wall by an α-adrenergic blockade reduces the spectral power of the LF and VLF ranges (Cerutti et al 1991;Japundzic et al 1990;Stauss et al 1995).…”