title: Estimating sympathetic tone by recording subcutaneous nerve activity in ambulatory dogs.
abstract: BACKGROUND
  We tested the hypothesis that subcutaneous nerve activity (SCNA) of the thorax correlates with the stellate ganglion nerve activity (SGNA) and can be used to estimate the sympathetic tone.
  
  
  RESULTS
  We implanted radio transmitters in 11 ambulatory dogs to record left SGNA, left thoracic vagal nerve activity (VNA), and left thoracic SCNA, including 3 with simultaneous video monitoring and nerve recording. Two additional dogs were studied under general anesthesia with apamin injected into the right stellate ganglion while the right SGNA and the right SCNA were recorded. There was a significant positive correlation between integrated SGNA (iSGNA) and integrated SCNA (iSCNA) in the first 7 ambulatory dogs, with correlation coefficient of 0.70 (95% confidence interval [CI] 0.61-0.84, P < 0.05 for each dog). Tachycardia episodes (heart rate exceeding 150 bpm for ≥3 seconds) were invariably preceded by SGNA and SCNA. There was circadian variation of both SCNA and SGNA. Crosstalk was ruled out because SGNA, VNA, and SCNA bursts had different timing and activation patterns. In an eighth dog, closely spaced bipolar subcutaneous electrodes also recorded SCNA, but with reduced signal to noise ratio. Video monitoring in additional 3 dogs showed that movement was not a cause of high frequency SCNA. The right SGNA correlated strongly with right SCNA and heart rate in 2 anesthetized dogs after apamin injection into the right stellate ganglion.
  
  
  CONCLUSIONS
  SCNA recorded by bipolar subcutaneous electrodes correlates with the SGNA and can be used to estimate the sympathetic tone.
authors.affiliation: Division of Cardiology, Department of Medicine, Krannert Institute of Cardiology, Indianapolis, Indiana, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Robinson
authors.forename: Kyoung-Suk
authors.initials: KS
authors.lastname: Rhee
authors.forename: Anisiia
authors.initials: A
authors.lastname: Doytchinova
authors.forename: Mohineesh
authors.initials: M
authors.lastname: Kumar
authors.forename: Richard
authors.initials: R
authors.lastname: Shelton
authors.forename: Zhaolei
authors.initials: Z
authors.lastname: Jiang
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Kamp
authors.forename: David
authors.initials: D
authors.lastname: Adams
authors.forename: David
authors.initials: D
authors.lastname: Wagner
authors.forename: Changyu
authors.initials: C
authors.lastname: Shen
authors.forename: Lan S
authors.initials: LS
authors.lastname: Chen
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Everett
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fishbein
authors.forename: Shien-Fong
authors.initials: SF
authors.lastname: Lin
authors.forename: Peng-Sheng
authors.initials: PS
authors.lastname: Chen
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002940:Circadian Rhythm; D004195:Disease Models, Animal; D004285:Dogs; D006339:Heart Rate; D007150:Immunohistochemistry; D008124:Locomotion; D011237:Predictive Value of Tests; D012815:Signal Processing, Computer-Assisted; D013233:Stellate Ganglion / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000201:enzymology / Q000503:physiopathology*; D013610:Tachycardia / Q000175:diagnosis* / Q000201:enzymology / Q000503:physiopathology*; D013686:Telemetry / Q000295:instrumentation; D013900:Thoracic Nerves / Q000201:enzymology / Q000503:physiopathology*; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis; D014630:Vagus Nerve / Q000503:physiopathology; D014741:Video Recording
chemical_list: D015415:Biomarkers; D014446:Tyrosine 3-Monooxygenase
keywords: autonomic ganglia; autonomic nervous system; cardiac arrhythmia; sympathetic tone; tachycardia; vagus
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