RESUMO
Spectral analysis was used to study the dynamics of low-frequency hemodynamic fluctuations in male Wistar rats following 2-wk tail-suspension. The experiment was performed with intact rats and rats with the sympathetic nervous system damaged by 6-hydroxidofamine injection. Equally in intact and desympathetized animals, low-frequency fluctuations of arterial pressure (AP) were found less intensive within the 0.1 Hz region during and immediately after suspension. Beyond that, the intact rats exhibited decreases in the AP fluctuations coherence and pulse interval in this spectral region. Results of the investigation indicate that simulated gravitational unloading of rats produces changes in the dynamics of the low-frequency AP fluctuations; however, some part of these changes are not controlled by the sympathetic nervous system.
Assuntos
Pressão Sanguínea/fisiologia , Frequência Cardíaca/fisiologia , Elevação dos Membros Posteriores/fisiologia , Simpatectomia/métodos , Animais , Gravitação , Masculino , Modelos Biológicos , Ratos , Ratos Wistar , Fatores de TempoRESUMO
In stimulation of the rat nerve with a modulated sine pattern, an increase in the modulating frequency from 0.03 to 0.15 Hz diminished the latency between the stimulating signals and changes in the vessel resistance as well as the amplitude of the flow oscillations, but did not affect tonic contractions of the vessel. A reduction of transmural pressure from 80 to 40 mm Hg increased both the tonic and the phasic components of the vessel contraction. Following the endothelium removal no change in the response latency occurred. The data obtained suggest that, during a rhythmic neurogenic influence, the vascular endothelium may work as an "amplifier" of the vessel's phasic contractions.
