Spontaneous muscle action potentials are blocked by N-type and P/Q-calcium channels blockers in the rat spinal cord–muscle co-culture system

2005 ◽  
Vol 1034 (1-2) ◽  
pp. 62-70 ◽  
Author(s):  
Kyoji Taguchi ◽  
Masatoshi Shiina ◽  
Keiko Shibata ◽  
Iku Utsunomiya ◽  
Tadashi Miyatake
Keyword(s):  
Spinal Cord ◽  
Calcium Channels ◽  
Action Potentials ◽  
Culture System ◽  
Muscle Action ◽  
Rat Spinal Cord ◽  
Calcium Channels Blockers

Relationships between the changes in compound muscle action potentials and selective injuries to the spinal cord and spinal nerve roots

2003 ◽  
Vol 114 (8) ◽  
pp. 1431-1436 ◽  
Author(s):  
Shunji Tsutsui ◽  
Tetsuya Tamaki ◽  
Hiroshi Yamada ◽  
Hiroshi Iwasaki ◽  
Masanari Takami
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Spinal Nerve ◽  
Muscle Action ◽  
Spinal Nerve Roots ◽  
Nerve Roots ◽  
Compound Muscle Action Potentials

Propagation of action potentials in the dendrites of neurons from rat spinal cord slice cultures

1996 ◽  
Vol 75 (1) ◽  
pp. 154-170 ◽  
Author(s):  
M. E. Larkum ◽  
M. G. Rioult ◽  
H. R. Luscher
Keyword(s):  
Spinal Cord ◽  
Action Potential ◽  
Calcium Imaging ◽  
Action Potentials ◽  
Synaptic Activity ◽  
Rat Spinal Cord ◽  
Voltage Sensitive Dye ◽  
Single Action ◽  
Before And After ◽  
Time Courses

1. We examined the propagation of action potentials in the dendrites of ventrally located presumed motoneurons of organotypic rat spinal cord cultures. Simultaneous patch electrode recordings were made from the dendrites and somata of individual cells. In other experiments we visualized the membrane voltage over all the proximal dendrites simultaneously using a voltage-sensitive dye and an array of photodiodes. Calcium imaging was used to measure the dendritic rise in Ca2+ accompanying the propagating action potentials. 2. Spontaneous and evoked action potentials were recorded using high-resistance patch electrodes with separations of 30-423 microm between the somatic and dendritic electrodes. 3. Action potentials recorded in the dendrites varied considerably in amplitude but were larger than would be expected if the dendrites were to behave as passive cables (sometimes little or no decrement was seen for distances of > 100 microm). Because the amplitude of the action potentials in different dendrites was not a simple function of distance from the soma, we suggest that the conductance responsible for the boosting of the action potential amplitude varied in density from dendrite to dendrite and possibly along each dendrite. 4. The dendritic action potentials were usually smaller and broader and arrived later at the dendritic electrode than at the somatic electrode irrespective of whether stimulation occurred at the dendrite or soma or as a result of spontaneous synaptic activity. This is clear evidence that the action potential is initiated at or near the soma and spreads out into the dendrites. The conduction velocity of the propagating action potential was estimated to be 0.5 m/s. 5. The voltage time courses of previously recorded action potentials were generated at the soma using voltage clamp before and after applying 1 microM tetrodotoxin (TTX) over the soma and dendrites. TTX reduced the amplitude of the action potential at the dendritic electrode to a value in the range expected for dendrites that behave as passive cables. This indicates that the conductance responsible for the actively propagating action potentials is a Na+ conductance. 6. The amplitude of the dendritic action potential could also be initially reduced more than the somatic action potential using 1-10 mM QX-314 (an intracellular sodium channel blocker) in the dendritic electrode as the drug diffused from the dendritic electrode toward the soma. Furthermore, in some cases the action potential elicited by current injection into the dendrite had two components. The first component was blocked by QX-314 in the first few seconds of the diffusion of the blocker. 7. In some cells, an afterdepolarizing potential (ADP) was more prominent in the dendrite than in the soma. This ADP could be reversibly blocked by 1 mM Ni2+ or by perfusion of a nominally Ca2+-free solution over the soma and dendrites. This suggests that the back-propagating action potential caused an influx of Ca2+ predominantly in the dendrites. 8. With the use of a voltage-sensitive dye (di-8-ANEPPS) and an array of photodiodes, the action potential was tracked along all the proximal dendrites simultaneously. The results confirmed that the action potential propagated actively, in contrast to similarly measured hyperpolarizing pulses that spread passively. There were also indications that the action potential was not uniformly propagated in all the dendrites, suggesting the possibility that the distribution of Na+ channels over the dendritic membrane is not uniform. 9. Calcium imaging with the Ca2+ fluorescent indicator Fluo-3 showed a larger percentage change in fluorescence in the dendrites than in the soma. Both bursts and single action potentials elicited sharp rises in fluorescence in the proximal dendrites, suggesting that the back-propagating action potential causes a concomitant rise in intracellular calcium concentration...

Intracellular recording from visually identified motoneurons in rat spinal cord slices

1978 ◽  
Vol 202 (1148) ◽  
pp. 417-421 ◽  
Keyword(s):  
Spinal Cord ◽  
Neuronal Activity ◽  
Intracellular Recording ◽  
Action Potentials ◽  
Intracellular Recordings ◽  
Rat Spinal Cord ◽  
Local Sensitivity ◽  
New Born ◽  
Intracellular Stimulation ◽  
Stimulation Of

Motoneurons were directly visualized with Nomarski optics in slices prepared from new born rat spinal cord. Intracellular recordings from these neurons showed spontaneous potentials, probably triggered by inter-neuronal activity. Action potentials could also be evoked by direct intracellular stimulation of the motoneurons. Iontophoretically applied L-glutamate caused a fast depolarization of the motoneuronal membrane. Considerable differences in local sensitivity to L-glutamate were found on the surface of the motoneuron.

A Novel In Vitro Approach for Studying the Segmental Motor System

Physiology ◽  
1992 ◽  
Vol 7 (6) ◽  
pp. 249-253
Author(s):  
H-R Luscher ◽  
J Streit
Keyword(s):  
Spinal Cord ◽  
Culture System ◽  
In Vitro Model ◽  
Organotypic Culture ◽  
Rat Spinal Cord ◽  
Structural And Functional Properties ◽  
Spinal Cord Dorsal ◽  
Vitro Model

An organotypic culture system of rat spinal cord, dorsal root ganglia, and skeletal muscle is presented that develops and preserves many structural and functional properties of the in vivo spinal cord. This in vitro model enlarges the methodological repertoire of mammalian spinal cord physiology and is ideally suited for studying developmental aspects.

Contribution of Fast and Slow Conducting Myelinated Axons to Single-Peak Compound Action Potentials in Rat Spinal Cord White Matter Preparations

2011 ◽  
Vol 105 (2) ◽  
pp. 929-941 ◽  
Author(s):  
Alexander A. Velumian ◽  
Yudi Wan ◽  
Marina Samoilova ◽  
Michael G. Fehlings
Keyword(s):  
Spinal Cord ◽  
White Matter ◽  
Action Potentials ◽  
Lower Threshold ◽  
Differential Sensitivity ◽  
Single Peak ◽  
Rat Spinal Cord ◽  
Conducting Component ◽  
Compound Action Potentials ◽  
Compound Action

Unlike recordings derived from optic nerve or corpus callosum, compound action potentials (CAPs) recorded from rodent spinal cord white matter (WM) have a characteristic single-peak shape despite the heterogeneity of axonal populations. Using a double sucrose gap technique, we analyzed the CAPs recorded from dorsal, lateral, and ventral WM from mature rat spinal cord. The CAP decay was significantly prolonged with increasing stimulus intensities suggesting a recruitment of higher threshold, slower conducting axons. At 3.5 mm conduction distance, a hidden higher threshold, slower conducting component responsible for prolongation of CAP decay was uncovered in 22 of 25 of dorsal WM strips by analyzing the stimulus-response relationships and a normalization-subtraction procedure. This component had a peak conduction velocity (CV) of 5.0 ± 0.2 (SE) m/s as compared with 9.3 ± 0.5 m/s for the lower threshold peak ( P < 0.0001). Oxygen-glucose deprivation (OGD), along with its known effects on CAP amplitude, significantly ( P < 0.015) shortened the CAP decay. The hidden higher threshold, slower conducting component showed greater sensitivity to OGD compared with the lower threshold, faster conducting component, suggesting a differential sensitivity of axonal populations of spinal cord WM. At longer conduction distances and lower temperatures (9.8 mm, 22–24°C), the slower peak could be directly visualized in CAPs at higher stimulation intensities. A detailed analysis of single-peak CAPs to identify their fast and slow conducting components may be of particular importance for studies of axonal physiology and pathophysiology in small animals where the conduction distance is not sufficiently long to separate the CAP peaks.

PS-36-9 Intraspinal mechanism of facilitation on the muscle action potentials elicited by paired stimulation to the spinal cord

1995 ◽  
Vol 97 (4) ◽  
pp. S176-S177
Author(s):  
Hiroaki Nishiura ◽  
Muneharu Ando ◽  
Hiroshi Yamada ◽  
Yasushi Tohge ◽  
Akira Ishiguchi ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Muscle Action ◽  
Paired Stimulation

Spatiotemporal Patterns of Dorsal Root–Evoked Network Activity in the Neonatal Rat Spinal Cord: Optical and Intracellular Recordings

2005 ◽  
Vol 94 (3) ◽  
pp. 1952-1961 ◽  
Author(s):  
Lea Ziskind-Conhaim ◽  
Stephen Redman
Keyword(s):  
Spinal Cord ◽  
Action Potentials ◽  
Dorsal Root ◽  
Spatiotemporal Patterns ◽  
Neonatal Rat ◽  
Network Activity ◽  
Rat Spinal Cord ◽  
Optical Signals ◽  
Postsynaptic Potentials ◽  
Neuronal Ensembles

Spatiotemporal patterns of dorsal root–evoked potentials were studied in transverse slices of the rat spinal cord by monitoring optical signals from a voltage-sensitive dye with multiple-photodiode optic camera. Typically, dorsal root stimulation generated two basic waveforms of voltage images: dual-component images consisting of fast, spike-like signal followed by a slow signal in the dorsal horn, and small, slow signals in the ventral horn. To qualitatively relate the optical signals to membrane potentials, whole cell recordings were combined with measurements of light absorption in the area around the soma. The slow optical signals correlated closely with subthreshold postsynaptic potentials in all regions of the cord. The spike-like component was not associated with postsynaptic action potentials, suggesting that the fast signal was generated by presynaptic action potentials. Firing in a single neuron could not be detected optically, implying that local voltage images originated from synchronously activated neuronal ensembles. Blocking glutamatergic synaptic transmission inhibited excitatory postsynaptic potentials (EPSPs) and significantly reduced the slow optical signals, indicating that they were mediated by glutamatergic synapses. Suppressing glycine-mediated inhibition increased the amplitude of both optical signals and EPSPs, while blocking GABAA receptor–mediated synapses, increased the amplitude and time course of EPSPs and prolonged the duration of voltage images in larger areas of the slice. The close correlation between evoked EPSPs and their respective local voltage images shows the advantage of the high temporal resolution optical system in measuring both the spatiotemporal dynamics of segmental network excitation and integrated potentials of neuronal ensembles at identified sites.

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