Spontaneous and transmitter-induced rhythmic activity in neonatal rat sympathetic preganglionic neurons in vitro.
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)
Shen
E
E
Department of Anatomy, Medical College of Ohio, Toledo 43614.
Wu
S Y
SY
Dun
N J
NJ
D000818:Animals; D000831:Animals, Newborn; D001339:Autonomic Fibers, Preganglionic / Q000502:physiology*; D001933:Brain Stem / Q000502:physiology*; D015220:Calcium Channels / Q000502:physiology; D046508:Culture Techniques; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005728:Ganglia, Sympathetic / Q000502:physiology*; D008125:Locus Coeruleus / Q000502:physiology; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology; D018377:Neurotransmitter Agents / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D015220:Calcium Channels; D018377:Neurotransmitter Agents; D015222:Sodium Channels