CALCIUM ACTIVATED RELEASE OF NITRIC OXIDE POTENTIATES EXCITATORY SYNAPTIC
POTENTIALS IN IMMATURE RAT SYMPATHETIC PREGANGLIONIC NEURONST.
Wu, S.Y. and N. J. Dun.
Department of Anatomy & Neurobiology, Medical College of Ohio, 3000
Arlington Avenue, Toledo, OH 43614 USA.
APStracts 2:0175N, 1995.
SUMMARY AND CONCLUSIONS
1. Whole-cell patch recordings were made from sympathetic preganglionic
neurons (SPNs), the majority of which contain brain nitric oxide synthase
(bNOS), in transverse spinal cord slices of 12-16 day old rats. 2. Repetitive
discharge of SPNs induced by a train of depolarizing current pulses (40 Hz, 10
sec) was followed by a long-lasting increase (140 +/- 22%) of the amplitude of
excitatory postsynaptic potentials (EPSPs) evoked by stimulation of lateral
funiculus in 50 of 75 SPNs. 3. In slices pretreated with the nitric oxide
synthase inhibitors, N G -monomethyl-L-arginine (L-NMA;100 [mu]M) or N w -
nitro-L-arginine (L-NARG; 30 [mu]M) or with bovine hemoglobin (100 [mu]M),
repetitive discharge of SPNs was not followed by a significant increase of
EPSPs. 4. Superfusing the slices with L-arginine (L-Arg, 300 [mu]M) but not D-
Arg reversibly increased the EPSPs by an average of 140 +/- 19%. 5. Inclusion
of the Ca 2+ chelator 1,2-bis (2-aminophenoxy)ethane-N,N,N',N'-tetraacetic
acid (BAPTA,1 mM) in the patch-electrodes resulted in no significant increase
of EPSPs following repetitive discharge in all cells studied. 6. It is
concluded that during repetitive discharge of SPNs, Ca 2+ influx via voltage-
gated channels activates bNOS, resulting in a release of nitric oxide and
potentiation of EPSPs.
Received 19 December 1994; accepted in final form 20 March 1995.
APS Manuscript Number J789-4.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.