Rhythmic sympathetic nerve discharges in an in vitro neonatal rat
brainstem-spinal cord preparation.
Su., Chun-Kuei.
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
11529, Republic of China
APStracts 6:0246A, 1999.
To understand the origination of sympathetic nerve discharge (SND), we
develop an in vitro brainstem-spinal cord preparation from neonatal
rats. Ascorbic acid (3 mM) was added into the bath solution to
increase the viability of preparations. At 24 C, rhythmic SND
(recorded from the splanchnic nerve) was consistently observed but
became quiescent at <16 C. Respiratory-related SND (rSND) was
discernible and well-correlated with C4 root activity. Power spectral
analysis of SND revealed a dominant 2 Hz oscillation. In most
preparations (86%), such oscillation was persistent while only
slightly reduced its magnitude after isolation from the brainstem.
The removal of neural structures rostral to the superior cerebellar
artery (equivalent to the level of facial nuclei) reduced rSND,
increased tonic SND, but did not affect the temporal coupling between
SND and C4 root activity. Our data suggest a prominent contribution
of SND from the neural mechanisms confined within the neonatal rat
spinal cord. This ascorbic acid enhanced in vitro preparation is a
very useful model to study neural mechanisms underlying
sympathorespiratory integration.
Received 25 January 1999; accepted in final form 21 May 1999.
APS Manuscript Number A051-9.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 14 June 1999