Although baroreceptors are known to reset to operate in a higher pressure range in spontaneously hypertensive rats (SHR), the total profile of dynamic arterial pressure (AP) regulation remains to be clarified. We estimated open-loop transfer functions of the carotid sinus baroreflex in SHR and Wistar Kyoto (WKY) rats. Mean input pressures were set at 120 (WKY120 and SHR120) and 160 mmHg (SHR160). The neural arc transfer function from carotid sinus pressure to efferent splanchnic sympathetic nerve activity (SNA) revealed derivative characteristics in both WKY and SHR. The slope of dynamic gain (in decibels per decade) between 0.1 and 1 Hz was not different between WKY120 (10.1 ± 1.0) and SHR 120 (10.4 ± 1.1) but was significantly greater in SHR 160 (13.2 ± 0.8, P < 0.05 with Bonferroni correction) than in SHR 120. The peripheral arc transfer function from SNA to AP showed low-pass characteristics. The slope of dynamic gain (in decibels per decade) did not differ between WKY 120 (-34.0 ± 1.2) and SHR 120 (-31.4 ± 1.0) or between SHR 120 and SHR 160 (-32.8 ± 1.3). The total baroreflex showed low-pass characteristics and the dynamic gain at 0.01 Hz did not differ between WKY 120 (0.91 ± 0.08) and SHR 120 (0.84 ± 0.13) or between SHR 120 and SHR 160 (0.83 ± 0.11). In both WKY and SHR, the declining slope of dynamic gain was significantly gentler for the total baroreflex than for the peripheral arc, suggesting improved dynamic AP response in the total baroreflex. In conclusion, the dynamic characteristics of AP regulation by the carotid sinus baroreflex were well preserved in SHR despite significantly higher mean AP.
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|Publication status||Published - Jan 2011|
- Arterial pressure
- Sympathetic nerve activity
- Systems analysis
- Transfer function
- White noise