Journal of Neurophysiology, Vol 71, Issue 3 1197-1205, Copyright © 1994 by APS

ARTICLES

Spontaneous and transmitter-induced rhythmic activity in neonatal rat sympathetic preganglionic neurons in vitro

E. Shen, S. Y. Wu and N. J. Dun
Department of Anatomy, Medical College of Ohio, Toledo 43614.

1. Intracellular recordings were made from sympathetic preganglionic neurons (SPNs) in transverse thoracolumbar spinal cord slices of 12- to 16-day-old rats. 2. A population of SPNs exhibited spontaneous, rhythmic activities that can be grouped into regular firing, bursting, or tonic oscillatory mode; the spikes were interspersed with subthreshold afterdepolarizing potentials (ADPs). 3. Spontaneous activities were not abolished by the excitatory amino acid antagonists 6-cyano-7-nitroquinoxoline-2,3-dione (CNQX, 10-20 microM) and D-2-amino-5-phosphonovaleric acid (APV, 10-20 microM) nor by the inhibitory amino acid antagonists bicuculline (10-30 microM) and strychnine (1 microM). 4. Stimulation of lateral funiculus elicited a CNQX-sensitive excitatory postsynaptic potential (EPSP) in the majority of spontaneously active SPNs tested. Moreover, rhythmic activities could be triggered by stimulation of lateral funiculus in 8 of the 80 otherwise quiescent SPNs tested. 5. Spontaneous spikes and ADPs were abolished by either Na(+)-free or tetrodotoxin (TTX, 0.5 microM)-containing Krebs solution. 6. The spontaneous spike afterhyperpolarization (AH) consisted of two components: a fast AHf and a slower AHS with a mean half decay time of 74.5 +/- 10.2 and 153.8 +/- 15.4 (SD) ms, respectively. 7. Superfusing the slices with a Ca(2+)-free Krebs solution or Krebs solution containing tetraethylammonium (TEA, 10-30 mM) preferentially blocked the AHS, thereby increasing the spontaneous discharge frequency. 8. Caffeine (3 mM) initially prolonged the AHS, thereby slowing the discharge frequency; the spontaneous discharges were eventually obliterated in the continuous presence of caffeine.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				J. H. Coote Landmarks in understanding the central nervous control of the cardiovascular system Exp Physiol, January 1, 2007; 92(1): 3 - 18. [Abstract] [Full Text] [PDF]

				Y.-W. Cheng, M.-C. Ku, C.-M. Ho, C.-Y. Chai, and C.-K. Su GABAB-receptor-mediated suppression of sympathetic outflow from the spinal cord of neonatal rats J Appl Physiol, November 1, 2005; 99(5): 1658 - 1667. [Abstract] [Full Text] [PDF]

				V. R. Antunes, G. C. Brailoiu, E. H. Kwok, P. Scruggs, and N. J. Dun Orexins/hypocretins excite rat sympathetic preganglionic neurons in vivo and in vitro Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2001; 281(6): R1801 - R1807. [Abstract] [Full Text] [PDF]

				C.-C. Lai, S. Y. Wu, C.-T. Chen, and N. J. Dun Nociceptin inhibits rat sympathetic preganglionic neurons in situ and in vitro Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2000; 278(3): R592 - R597. [Abstract] [Full Text] [PDF]