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Immunocytochemical and electrophysiological techniques were used to localize TTX-sensitive sodium channels (NaChs) over the soma-dendritic axis of basilar and nonbasilar pyramidal cells of the electrosensory lateral line lobe (ELL) of weakly electric fish (Apteronotus leptorhynchus). Dense NaCh-like immunolabel was detected on the membranes of basilar and nonbasilar pyramidal cell somata. Punctate regions of immunolabel (approximately 15 microns) were separated by nonlabeled expanses of membrane over the entire extent of basal dendrites. Similar punctate immunolabel was observed over the apical dendrites, and frequently on membranes of afferent parallel fiber boutons in the distal apical dendritic region. Intracellular recordings from pyramidal cell somata or proximal apical dendrites (75-200 microns) were obtained using an in vitro ELL slice preparation. TTX-sensitive potentials were identified by focal pressure ejection of TTX. Somatic recordings demonstrated both TTX-sensitive fast spike discharge and a slow prepotential; similar but lower amplitude potentials were recorded in apical dendrites. Dendritic spikes were composed of at least two active components triggered by a fast prepotential (FPP) generated by the somatic spike. TTX-sensitive spikes propagated in a retrograde fashion over at least the proximal 200 microns of the apical dendrites, as determined by the conduction of an antidromic population spike and focal TTX ejections. Somatic spikes were followed by a depolarizing afterpotential (DAP) that was similar in duration and refractory period to that of proximal dendritic spikes. During repetitive spike discharge, the DAP could increase in amplitude and attain somatic spike threshold, generating a high-frequency spike doublet and a subsequent hyperpolarization that terminated spike discharge. Repetition of this process gave rise to an oscillatory burst discharge (2-6 spikes/burst) with a frequency of 40-80 Hz. Both the DAP and oscillatory discharge were selectively blocked by TTX ejections restricted to the proximal apical dendritic region. The present study demonstrates an immunolocalization of NaChs over somatic and dendritic membranes of a vertebrate sensory neuron that correlates with the distribution of TTX-sensitive potentials. The interaction of somatic and dendritic action potentials is further shown to underlie an oscillatory discharge believed to be important in electrosensory processing.
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
May 1992,
Science (New York, N.Y.),
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
November 1998,
Journal of neuroscience research,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
July 1987,
Neuroscience letters,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
April 2017,
Journal of neurophysiology,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
June 2004,
The Journal of biological chemistry,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
December 2001,
Neuroreport,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
November 1988,
The Journal of neuroscience : the official journal of the Society for Neuroscience,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
April 2000,
Molecular and cellular neurosciences,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
December 1998,
Nature neuroscience,
R W Turner, and
L Maler, and
T Deerinck, and
S R Levinson, and
M H Ellisman
January 2014,
Handbook of experimental pharmacology,
