Linked Life Data

9306279

Source:http://linkedlifedata.com/resource/pubmed/id/9306279

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1997-11-19
pubmed:abstractText
1. Voltage-gated Na+ channels and their distribution were studied by the patch-clamp technique in intact dorsal horn neurones in slices of newborn rat spinal cord and in neurones isolated from the slice by slow withdrawal of the recording pipette. This new method of neurone isolation was further used to study the roles of soma and axon in generation of action potentials. 2. Tetrodotoxin (TTX)-sensitive Na+ currents in intact neurones consisted of three components. A fast component with an inactivation time constant (tau f) of 0.6-2.0 ms formed the major part (80-90%) of the total Na+ current. The remaining parts consisted of a slowly inactivating component (tau s of 5-20 ms) and a steady-state component. 3. Single fast and slow inactivating Na+ channels with conductances of 11.6 and 15.5 pS, respectively, were identified in the soma of intact neurones in the slice. Steady-state Na+ channels were not found in the soma, suggesting an axonal or dendritic localization of these channels. 4. In the whole-cell recording mode, the entire soma of a dorsal horn neurone could be isolated from the slice by slow withdrawal of the recording pipette, leaving all or nearly all of its processes in the slice. The isolated structure was classified as: (1) 'soma' if it lost all of its processes, (2) 'soma+axon' complex if it preserved one process and at least 85% of its original peak Na+ current or (3) 'soma+dendrite' complex if it preserved one process but the remaining Na+ current did not exceed those observed in the isolated 'somata'. 5. The spatial distribution of Na+ channels in the neurone was studied by comparing Na+ currents recorded before and after isolation. The isolated 'soma' contained 13.8 +/- 1.3% of inactivating Na+ current but no steady-state Na+ current. 'Soma+axon' complexes contained 93.6 +/- 1.4% of inactivating and 46% of steady-state Na+ current. 6. In current-clamp experiments, the intact neurones and isolated 'soma+axon' complexes responded with 'all-or-nothing' action potentials to current injections. In contrast, isolated 'somata' showed only passive or local responses and were unable to generate action potentials. 7. It is concluded that dorsal horn neurones of the spinal cord possess three types of TTX-sensitive voltage-gated Na+ channels. The method of entire soma isolation described here shows that the majority of inactivating Na+ channels are localized in the axon hillock and only a small proportion (ca 1/7) are distributed in the soma. Steady-state Na+ channels are most probably expressed in the axonal and dendritic membranes. The soma itself is not able to generate action potentials. The axon or its initial segment plays a crucial role in the generation of action potentials.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-106074, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-1359126, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2388151, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2408712, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2430289, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2446328, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2452862, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2454285, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2555170, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2561976, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-2780225, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-3696498, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-447880, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-571107, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-6197429, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-6270629, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-6286901, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-6306228, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-7473261, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-7536092, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-7576650, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-7952286, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-7970226, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8015385, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8107777, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8351200, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8381170, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8592214, http://linkedlifedata.com/resource/pubmed/commentcorrection/9306279-8815799
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-3751
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
503 ( Pt 2)
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
371-85
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Functional distribution of three types of Na+ channel on soma and processes of dorsal horn neurones of rat spinal cord.
pubmed:affiliation
Physiologisches Institut, Justus-Liebig-Universität Giessen, Germany. Boris.Safronov@physiologie.med.uni-giessen.de
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't