title: Cervical vagal nerve stimulation activates the stellate ganglion in ambulatory dogs.
abstract: OBJECTIVE
  Recent studies showed that, in addition to parasympathetic nerves, cervical vagal nerves contained significant sympathetic nerves. We hypothesized that cervical vagal nerve stimulation (VNS) may capture the sympathetic nerves within the vagal nerve and activate the stellate ganglion.
  
  
  METHODS
  We recorded left stellate ganglion nerve activity (SGNA), left thoracic vagal nerve activity (VNA), and subcutaneous electrocardiogram in seven dogs during left cervical VNS with 30 seconds on-time and 30 seconds off time. We then compared the SGNA between VNS on and off times.
  
  
  RESULTS
  Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation. Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation. The differences of integrated SGNA and integrated VNA between VNS on and off times (ΔSGNA) increased progressively from 5.2 mV-s {95% confidence interval (CI): 1.25-9.06, p=0.018, n=7} at 1.0 mA to 13.7 mV-s (CI: 5.97-21.43, p=0.005, n=7) at 1.5 mA. The difference in HR (ΔHR, bpm) between on and off times was 5.8 bpm (CI: 0.28-11.29, p=0.042, n=7) at 1.0 mA and 5.3 bpm (CI 1.92 to 12.61, p=0.122, n=7) at 1.5 mA.
  
  
  CONCLUSIONS
  Intermittent cervical VNS may selectively capture the sympathetic components of the vagal nerve and excite the stellate ganglion at moderate output. Increasing the output may result in simultaneously sympathetic and parasympathetic capture.
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. ; Department of Internal Medicine, Chonbuk National University School of Medicine, Jeonju, Korea.
authors: Kyoung-Suk
authors: KS
authors: Rhee
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Chia-Hsiang
authors: CH
authors: Hsueh
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Jessica A
authors: JA
authors: Hellyer
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. ; Department of Cardiovascular Medicine, Chonnam National University Medical School, Gwangju, Korea.
authors: Hyung Wook
authors: HW
authors: Park
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA. ; Division of Cardiology, College of Medicine, Catholic University of Daegu, Daegu, Korea.
authors: Young Soo
authors: YS
authors: Lee
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Jason
authors: J
authors: Garlie
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Patrick
authors: P
authors: Onkka
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Anisiia T
authors: AT
authors: Doytchinova
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: John B
authors: JB
authors: Garner
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Jheel
authors: J
authors: Patel
authors: Department of Neurology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Lan S
authors: LS
authors: Chen
authors: Department of Pathology and Laboratory Medicine, The David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
authors: Michael C
authors: MC
authors: Fishbein
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Thomas
authors: T
authors: Everett
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Shien-Fong
authors: SF
authors: Lin
authors: Krannert Institute of Cardiology and Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Peng-Sheng
authors: PS
authors: Chen
keywords: Autonomic nervous system; Stellate ganglion; Vagus nerve stimulation