gms | German Medical Science

64th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

26 - 29 May 2013, Düsseldorf

Detecting and influencing baroreceptor activity in the vagal nerve of the rat

Meeting Abstract

  • Mortimer Gierthmuehlen - Abteilung Allgemeine Neurochirurgie, Universitätsklinikum Freiburg, Freiburg
  • Oscar Cota - Lehrstuhl für Biomedizinische Mikrotechnik, Institut für Mikrosystemtechnik (IMTEK), Albert-Ludwigs-Universität Freiburg, Freiburg
  • Thomas Stieglitz - Lehrstuhl für Biomedizinische Mikrotechnik, Institut für Mikrosystemtechnik (IMTEK), Albert-Ludwigs-Universität Freiburg, Freiburg; Bernstein Center Freiburg, Universität Freiburg, Freiburg
  • Josef Zentner - Abteilung Allgemeine Neurochirurgie, Universitätsklinikum Freiburg, Freiburg
  • Dennis Plachta - Lehrstuhl für Biomedizinische Mikrotechnik, Institut für Mikrosystemtechnik (IMTEK), Albert-Ludwigs-Universität Freiburg, Freiburg

Deutsche Gesellschaft für Neurochirurgie. 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Düsseldorf, 26.-29.05.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocMO.15.02

doi: 10.3205/13dgnc127, urn:nbn:de:0183-13dgnc1275

Published: May 21, 2013

© 2013 Gierthmuehlen et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Electrical stimulation of afferent vagal nerve fibers originating from the aortic pressure sensors can trigger the baroreflex and reduce blood pressure in rats. Since the vagal nerve is a very heterogeneous nerve that innervates multiple organs, a selective localization and stimulation of such baroreceptive fibers within the cross section of the vagal nerve is necessary. We demonstrate how a novel multichannel cuff-electrode and a new localization algorithm can selectively separate and stimulate baroreceptor fibers in the vagal nerve bundle of a rat.

Method: The left vagal nerve bundle was isolated and wrapped in a multichannel cuff-electrode in three male Wistar rats and a microtip transducer was inserted in the carotid artery. The surface potentials of the nerve bundle were registered using an impedance balanced true-tripolar technique. These data were then processed using a coherent averaging algorithm. Blood pressure recording and ECG triggered the coherent averaging. With ongoing coherent averaging the blood pressure correlated compound signal of the electrode-tripole proximal to the baroreflexive fibers was raised above noise level. The correlated electrode tripole was then used for a tripolar stimulation. During stimulation with different intensities, duration and repetition rates, the blood pressure and the heart rate, as well as the respiration rate were monitored.

Results: The novel multichannel cuff-electrode securely fit around the nerve bundle. The tripolar recording configuration delivered stable raw physiological data, from which our coherent averaging algorithm extracted the activity of baroreceptor fibers in the nerve bundle within 5 heart beats. Channel-selective tripolar stimulation (stimulation signal consists of 100 pulses at 30 Hz repetition rate, with a 0.8 mA charge balanced biphasic pulses with a pulse duration of 0.5 µs), reduced the blood pressure significantly (>30% of pre-stimulus MAP) for more than 6 seconds without significant effect on the heart rate or respiration.

Conclusions: Baroreceptor activity can be detected inside the vagal nerve bundle of the rat with our novel multichannel cuff-electrode and coherent averaging. Tripolar stimulation of these fibers can lower the blood pressure without triggering significant bradycardia or bradypnea. Advanced detection and stimulation algorithms will be investigated in larger animals, and selective vagal nerve stimulation will be evaluated as a possible technique to permanently lower elevated blood pressure.