Low-level neurostimulation of the renal nerves as a potential therapeutic strategy for hypertension treatment

Figures

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  FIGURE 1. Representative raw data traces showing the effect of 2.5 Hz (Left panel) and 5.0 Hz (right panel) renal nerve stimulation (RNS) at 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s in one anesthetized spontaneously hypertensive rat. Stimulation (Stim), arterial pressure (AP), heart rate (HR), hindquarter blood flow (HQF) and renal cortical blood flow (RCF).

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  FIGURE 2. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on mean arterial pressure (MAP) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for depressor responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in MAP at both frequencies relative to baseline. The right panel shows differences in absolute changes (mmHg) in MAP response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8).* P < 0.05 relative to respective baseline.

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  FIGURE 3. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on heart rate (HR) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for bradycardic responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in HR at both frequencies relative to baseline. The right panel shows differences in absolute changes (bpm) in HR response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8).

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  FIGURE 4. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on hindquarter blood flow (HQF) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for HQF responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in HQF at both frequencies relative to baseline. The right panel shows differences in absolute changes (mL.min-1) in HQF response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8). * P < 0.05 relative to respective baseline.

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  FIGURE 5. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on hindquarter vascular resistance (HQR) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for HQR responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in HQR at both frequencies relative to baseline. The right panel shows differences in absolute changes (mmHg.ml.min-1) in HQR response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8). * P < 0.05 relative to respective baseline.

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  FIGURE 6. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on ipsilateral renal cortical blood flow (RCF) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for RCF responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in RCF at both frequencies relative to baseline. The right panel shows differences in absolute changes (nu) in RCF response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8). * P < 0.05 relative to respective baseline and # P < 0.05 relative to 2.5 Hz.

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  FIGURE 7. Effect of renal nerve stimulation (RNS) at 2.5 and 5.0 Hz pulse frequency, 0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s on ipsilateral renal cortical vascular resistance (RCR) in anesthetized spontaneously hypertensive rats (SHRs). The left panel shows the time trend for RCR responses to RNS at 2.5 and 5.0 Hz. The middle panel shows differences in RCF at both frequencies relative to baseline. The right panel shows differences in absolute changes (mmHg.nu−1) in RCR response to RNS at 2.5 and 5.0 Hz. Results are expressed as mean ± SEM (n = 8). * P < 0.05 relative to respective baseline and # P < 0.05 relative to 2.5 Hz.

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  FIGURE 8. Correlation analysis of the relationship between maximal (upper panel) mean arterial pressure (MAP) versus heart rate (HR), and (lower panel) MAP and hindquarter vascular resistance (HQR) at 2.5 (open circle) and 5.0 Hz (closed circle) stimulation frequency (0.5 mA pulse amplitude, and 0.5 ms pulse width for 30 s) in anesthetized spontaneously hypertensive rats (SHRs, n = 8). r, Pearson’s correlation coefficient, and R 2, regression coefficient.