The electrophysiological effects of nitric oxide in the mouse
superior mesenteric ganglion.
Mazet, Bruno, Steven M. Miller, and Joseph H. Szurszewski.
Department of Physiology and Biophysics, Mayo Clinic and Mayo
Foundation, Rochester, MN 55905 USA
APStracts 2:0195G, 1995.
The effects of NO generated from sodium nitroprusside (SNP) on neurons
of the mouse superior mesenteric ganglion (SMG) were studied in vitro
using intracellular recording techniques. SNP solutions caused a
membrane hyperpolarization in the majority (64%) of the neurons
tested or a hyperpolarization followed by a depolarization in 8% of
the neurons tested. The SNP-induced hyperpolarization persisted in a
low Ca++-high Mg++ solution, indicating a direct effect of NO on the
postsynaptic membrane. The hyperpolarizing effect of SNP was reduced
or abolished by oxyhemoglobin. Electrical stimulation of the colonic
nerves evoked a late slow excitatory postsynaptic potential (late
sEPSP) in a population of neurons in normal Krebs solution. The
amplitude of the late sEPSP was significantly enhanced in the
presence of NG-nitro-L-arginine, a NO synthase inhibitor. The
results, particularly those observed with the NO synthase inhibitor,
suggest that endogenous NO was released in the mouse SMG by
repetitive nerve stimulation and that it modulated slow synaptic
transmission, presumably by a direct action on ganglionic neurons.
Received 21 November 1994; accepted in final form 4 September
1995.
APS Manuscript Number G457-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95