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Uneven distribution of K + channels in soma, axon and dendrites of rat spinal neurones: functional role of the soma in generation of action potentials
Author(s) -
Wolff Matthias,
Vogel Werner,
Safronov Boris V.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.767bm.x
Subject(s) - soma , axon , neuroscience , axon hillock , spinal cord , excitatory postsynaptic potential , antidromic , electrophysiology , postsynaptic potential , chemistry , anatomy , biophysics , biology , inhibitory postsynaptic potential , receptor , biochemistry
1 A novel method of ‘entire soma isolation’ was used to describe the distribution of voltage‐gated K + channels between soma, axon and dendrites of dorsal horn neurones identified in spinal cord slices of newborn rat. 2 The soma contained 36 % of total inactivating (K A ) current but only 15 % of delayed rectifier (K DR ) current. The axon initial segment possessed almost half (47 %) of the total K A current and 38 % of K DR current. In contrast, dendrites contained a small portion (17 %) of K A but 47 % of K DR current. 3 Under current‐clamp conditions, the soma isolated from axon and dendrites was not able to generate action potentials. It passively conducted weak (≤ ‐50 mV) and amplified pronounced (‐50 to 0 mV) depolarizations but inhibited strong (≤ 0 mV) depolarizations. 4 It is concluded that the soma plays a complex role in the excitability of spinal dorsal horn neurones. It conducts passively or amplifies excitatory postsynaptic potentials on their way from dendrites and soma to the axon initial segment but it inhibits back‐propagation of the action potential from the axon to the dendrites.