Key result
Left-sided cervical VNS caused greater bradycardia, hypotension, and tachypnea than right-sided VNS in hypertensive rats, with responses depending on voltage, frequency, and pulse duration.
Why the study?
Does left- or right-sided cervical vagal nerve stimulation produce different hemodynamic and respiratory responses in a hypertensive rat model?
Does left- or right-sided cervical vagal nerve stimulation produce different hemodynamic and respiratory responses in a hypertensive rat model?
In a hypertensive rat model, left-sided cervical VNS produces more pronounced cardio-respiratory responses than right-sided VNS, providing parameter guidance for future neuromodulation studies.
Greater left VNS responses in hypertensive rats warrant caution in clinical translation; leaves open side-specific parameter optimization for future neuromodulation studies.
Neuromodulation through vagal nerve stimulation (VNS) is currently explored for a variety of clinical conditions. However, there are no established VNS parameters for animal models of human diseases, such as hypertension. Therefore, the aim of this study was to assess hemodynamic and respiratory responses to right- or left-sided cervical VNS in a hypertensive rat model. Anesthetized stroke-prone spontaneously hypertensive rats were instrumented for arterial blood pressure and heart rate monitoring and left- or right-sided VNS. Cervical VNS was applied through bipolar coil electrodes. Stimulation parameters tested were 3 V and 6 V, 2 Hz to 20 Hz stimulation frequency, and 50 μsec to 20 msec pulse duration. Each combination of stimulation parameters was applied twice with altered polarity, that is, anode and cathode in the cranial and caudal position. Respiration rate was derived from systolic blood pressure fluctuations. In general, cervical VNS caused bradycardia, hypotension, and tachypnea. These responses were more pronounced with left-sided than with right-sided VNS and depended on the stimulation voltage, stimulation frequency, and pulse duration, but not on the polarity of stimulation. Furthermore, the results suggest that at low stimulation frequencies (<5 Hz) and short pulse durations (<0.5 msec) primarily larger A-fibers are activated, while at longer pulse durations (>0.5 msec) smaller B-fibers are also recruited. In conclusion, in rats left-sided cervical VNS causes greater cardio-respiratory responses than right-sided VNS and at lower stimulation frequencies (e.g., 5 Hz), longer pulse durations (>0.5 msec) seem to be required to consistently recruit B-fibers in addition to A-fibers.
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Harald M. Stauss (2017) studied Hypertension. Left-sided cervical vagal nerve stimulation vs. Right-sided cervical vagal nerve stimulation was evaluated on Hemodynamic and respiratory responses (bradycardia, hypotension, and tachypnea). Left-sided cervical VNS caused greater bradycardia, hypotension, and tachypnea than right-sided VNS in hypertensive rats, with responses depending on voltage, frequency, and pulse duration.
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