Varying frequency and pulse width duration during electrical stimulation of cervical sympathetic chain in Zucker Fat rats dramatically alters hemodynamics

Abstract

The influence of electrical stimulation of the cervical sympathetic chain (CSC) on hemodynamics has not been thoroughly investigated. Previous studies using healthy strains of rats focused on upper airway dynamics as well as ventilatory parameters. This current study examined the changes in mean blood pressure (MAP), diaphragmatic electromyogram (EMG), and upper airway pressure (UAP) elicited by electrical stimulation of the CSC in Zucker‐fat rats, a model of obesity‐hypertension,. Under urethane anesthesia, male Zucker‐Fat rats (16 weeks of age, n=4), were instrumented to continuously record MAP, diaphragmatic EMG), and UAP. Both CSC were dissected, isolated and stimulated at 0.5 mA, with varying frequency (2.5, 5, 7.5, 10 and 20 Hz) and pulse widths duration (0.1, 0.2, 0.5 and 2.0 ms). Both frequency and pulse‐width dependent depressor response was observed with bilateral CSC stimulation. Lower frequency stimulations produced a 5% decrease in MAP and 12% decrease in UAP whereas the highest frequency of 20 Hz (0.5 mA, 0.2 ms kept constant) produced a 20% decrease in MAP and 25% decrease in UAP relative to baseline (panel A). The smallest pulse width (0.1 ms) produced a 3% decrease in MAP and 5% decrease in UAP whereas 2 ms produced a 25% MAP drop and 10% drop in UAP relative to baseline measures (panel B). Diaphragmatic changes were negligible with CSC stimulation. We conclude that bilateral electrical stimulation of the CSC effectively lowers MAP and UAP in an obesity‐hypertension rat model. In addition, both frequency and pulse width parameters can vary the hemodynamic response dramatically. Future studies will investigate optimal stimulation parameters and whether stimulation can lower hypertension in conscious Zucker‐Fat rats.Support or Funding InformationSupported by NIH1OT2OD023860‐01, Galvani BioelectronicsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.