Regional Differences in Sympathetic Nerve Activity Are Generated by Multiple Arterial Baroreflex Loops Arranged in Parallel

Figures

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  FIGURE 1. Shifts in the baroreflex curves for renal sympathetic nerve activity (RSNA) in panel (A), lumbar sympathetic nerve activity (LSNA) in panel (B), and heart rate (HR) in panel (C) during the control and freezing periods. AP, arterial pressure. Symbols and bars indicate the mean and standard error of mean, respectively. The image was obtained with permission from the study by Kondo et al. (2021).

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  FIGURE 2. Changes in renal sympathetic nerve activity (RSNA) and lumbar sympathetic nerve activity (LSNA) during the transition from non-rapid eye movement (NREM) sleep (pre-REM) to REM sleep and from the REM sleep to NREM (post-REM) sleep periods. Continuous drawn lines represent mean values and shaded areas above and below show the standard error of mean. *p < 0.05 indicates a significant difference from the average level obtained during the pre-REM period. The image was obtained with permission from the study by Yoshimoto et al. (2011).

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  FIGURE 3. Relationship between renal sympathetic nerve activity (RSNA) and lumbar sympathetic nerve activity (LSNA) across the behavioral states. A significant (p < 0.05) linear relationship was observed between RSNA and LSNA (y = 0.72x + 27.76) in the non-rapid eye movement (NREM) sleep, quiet awake (Quiet), moving (Mov), and grooming (Groom) states. The relationship between RSNA and LSNA during the REM sleep and freezing period (Freez) was dissociated from the line obtained during other behavioral states. Values are shown as the mean ± standard error of the mean. The gray curved lines are the 95% confidence bands for the regression line. The image was obtained with permission from the studies by Yoshimoto et al. (2010; 2011).

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  FIGURE 4. Shifts in the baroreflex curves for renal sympathetic nerve activity (RSNA) during the pre-exercise, treadmill exercise, and post-exercise periods. The average oxygen consumption during treadmill exercise at a speed of 20 m/min with a 0% gradient performed in this study was 51 ml/min/kg, which was approximately 70% of the maximum oxygen consumption. The curves and bars indicate the mean and standard error of the mean, respectively, estimated over each 2.5-mmHg bin of arterial pressure (AP). The image was obtained with permission from the study by Miki et al. (2003).

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  FIGURE 5. Schematic diagram showing the role of parallel baroreflex loops in regulating sympathetic nerve activity and, thereby, arterial pressure (AP). Parallel baroreflex loops regulate heart rate (HR), renal sympathetic nerve activity (RSNA), and lumbar sympathetic nerve activity (LSNA) separately to generate region-specific changes in the SNA. Each arterial baroreflex loop receives similar stimulus information from the muscle ergoreceptors, but it receives separate and integrated information from the CNS above the medulla to optimize AP as a whole body.