NEURAL ARC OF BAROREFLEX OPTIMIZES DYNAMIC PRESSURE REGULATION IN ACHIEVING BOTH STABILITY AND QUICKNESS

The baroreflex loop consists of a fast neural are and a slow mechanica l arc. We hypothesized that the neural baroreflex are compensates the slow mechanical response and thus improves the quality of blood pressu re regulation. We estimated the open-loop transfer characteristics of the neural baroreflex are (H-n), i.e., from carotid sinus pressure to sympathetic nerve activity (SNA), and that of the effective peripheral baroreflex are (H-p), i.e., from SNA to arterial pressure, in anesthe tized rabbits. The gain of H-n was constant below 0.12 +/- 0.057 Hz an d increased with a slope of 6.1 +/- 0.06 dB/octave above its frequency up to 1 Hz. In contrast, the gain of H-p was constant below 0.071 +/- 0.03 Hz and decreased with a slope of -11.0 +/- 1.48 dB/octave above the frequency. These data indicate that H-n accelerates slow periphera l responses in the frequency range of 0.1-1 Hz. Although too much acce leration in the high-frequency range could result in instability of th e system, numerical analysis of the closed-loop baroreflex response in dicated that the neural are optimized arterial pressure regulation in achieving both stability and quickness.