TY - JOUR
T1 - The acetylcholine sensitivity of the surface membrane of multiply‐innervated parasympathetic ganglion cells in the mudpuppy before and after partial denervation.
AU - Roper, S.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1976/1/1
Y1 - 1976/1/1
N2 - The surface chemosensitivity to iontophoretically applied acetylcholine (ACh) of single nerve cells in the cardiac ganglion of the mudpuppy was examined. Some synapses on the neurones can be recognized in the living preparation with differential interference contrast optics. Identified synaptic regions of the ganglion cells were more sensitive to ACh than were other areas. The mean sensitivity of synaptic areas was 509 mV/nC, but that of random spots on the cell surface (which were mainly non synaptic) was only 190 mV/nC. The mean rise time of ACh responses at synapses was 23 msec and at random spots was 36 msec. These data suggest that the density of ACh receptors is highest under the synapses on the postsynaptic membrane. When some, but not all, of the presynaptic terminals on the ganglion cells are destroyed by cutting the vagus nerve, the sensitivity of the entire surface membrane to applied ACh increases. This increase in sensitivity reaches a maximum about 4-6 weeks after the operation. Synaptic transmission at excitatory collateral synapses which remain after vagal degeneration is not altered by this hypersensitivity. Neurones from ganglia which have been isolated and maintained in organ culture also become hypersensitive to applied ACh. This heightened chemosensitivity develops much faster in vitro; hypersensitivity in cultured ganglia becomes manifest within 4-5 days, in contrast with 4-6 weeks after vagus degeneration in vivo.
AB - The surface chemosensitivity to iontophoretically applied acetylcholine (ACh) of single nerve cells in the cardiac ganglion of the mudpuppy was examined. Some synapses on the neurones can be recognized in the living preparation with differential interference contrast optics. Identified synaptic regions of the ganglion cells were more sensitive to ACh than were other areas. The mean sensitivity of synaptic areas was 509 mV/nC, but that of random spots on the cell surface (which were mainly non synaptic) was only 190 mV/nC. The mean rise time of ACh responses at synapses was 23 msec and at random spots was 36 msec. These data suggest that the density of ACh receptors is highest under the synapses on the postsynaptic membrane. When some, but not all, of the presynaptic terminals on the ganglion cells are destroyed by cutting the vagus nerve, the sensitivity of the entire surface membrane to applied ACh increases. This increase in sensitivity reaches a maximum about 4-6 weeks after the operation. Synaptic transmission at excitatory collateral synapses which remain after vagal degeneration is not altered by this hypersensitivity. Neurones from ganglia which have been isolated and maintained in organ culture also become hypersensitive to applied ACh. This heightened chemosensitivity develops much faster in vitro; hypersensitivity in cultured ganglia becomes manifest within 4-5 days, in contrast with 4-6 weeks after vagus degeneration in vivo.
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U2 - 10.1113/jphysiol.1976.sp011240
DO - 10.1113/jphysiol.1976.sp011240
M3 - Article
C2 - 175155
AN - SCOPUS:0016873259
VL - 254
SP - 455
EP - 473
JO - Journal of Physiology
JF - Journal of Physiology
SN - 0022-3751
IS - 2
ER -