Voltage behavior along the irregular dendritic structure of morphologically and physiologically characterized vagal motoneurons in the guinea pig

1990 ◽  
Vol 63 (2) ◽  
pp. 333-346 ◽  
Author(s):  
R. Nitzan ◽  
I. Segev ◽  
Y. Yarom
Keyword(s):  
Steady State ◽  
Guinea Pig ◽  
Time Constant ◽  
Dendritic Structure ◽  
Input Resistance ◽  
Membrane Properties ◽  
Small Cells ◽  
Physiological Data ◽  
Motor Nucleus ◽  
Cable Length

1. Intracellular recordings from neurons in the dorsal motor nucleus of the vagus (vagal motoneurons, VMs) obtained in the guinea pig brain stem slice preparation were used for both horseradish peroxidase (HRP) labeling of the neurons and for measurements of their input resistance (RN) and time constant (tau 0). Based on the physiological data and on the morphological reconstruction of the labeled cells, detailed steady-state and compartmental models of VM were built and utilized to estimate the range of membrane resistivity, membrane capacitance, and cytoplasm resistivity values (Rm, Cm, and Ri, respectively) and to explore the integrative properties of these cells. 2. VMs are relatively small cells with a simple dendritic structure. Each cell has an average of 5.3 smooth (nonspiny), short (251 microns) dendrites with a low order (2) of branching. The average soma-dendritic surface area of VMs is 9,876 microns 2. 3. Electrically, VMs show remarkably linear membrane properties in the hyperpolarizing direction; they have an average RN of 67 +/- 23 (SD) M omega and a tau 0 of 9.4 +/- 4.1 ms. Several unfavorable experimental conditions precluded the possibility of faithfully recovering ("peeling") the first equalizing time constant (tau 1) and, thereby, of estimating the electrotonic length (Lpeel) of VMs. 4. Reconciling VM morphology with the measured RN and tau 0 through the models, assuming an Ri of 70 omega.cm and a spatially uniform Rm, yielded an Rm estimate of 5,250 omega.cm2 and a Cm of 1.8 microF/cm2. Peeling theoretical transients produced by these models result in an Lpeel of 1.35. Because of marked differences in the length of dendrites within a single cell, this value is larger than the maximal cable length of the dendrites and is twice as long as their average cable length. 5. The morphological and physiological data could be matched indistinguishably well if a possible soma shunt (i.e., Rm, soma less than Rm, dend) was included in the model. Although there is no unique solution for the exact model Rm, a general conclusion regarding the integrative capabilities of VM could be drawn. As long as the model is consistent with the experimental data, the average input resistance at the dendritic terminals (RT) and the steady-state central (AFT----S) and peripheral (AFS----T) attenuation factors are essentially the same in the different models. With Ri = 70 omega.cm, we calculated RT, AFS----T, and AFT----S to be, on the average, 580 M omega, 1.1, and 13, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of bradykinin on membrane properties of guinea pig bronchial parasympathetic ganglion neurons

2000 ◽  
Vol 278 (3) ◽  
pp. L485-L491 ◽  
Author(s):  
Radhika Kajekar ◽  
Allen C. Myers
Keyword(s):  
Guinea Pig ◽  
Sensory Nerve ◽  
Input Resistance ◽  
Inhibitory Effect ◽  
Membrane Properties ◽  
Alternative Mechanism ◽  
Induced Membrane ◽  
Parasympathetic Ganglion ◽  
Hoe 140 ◽  
Ganglion Neurons

The effect of bradykinin on membrane properties of parasympathetic ganglion neurons in isolated guinea pig bronchial tissue was studied using intracellular recording techniques. Bradykinin (1–100 nM) caused a reversible membrane potential depolarization of ganglion neurons that was not associated with a change in input resistance. The selective bradykinin B2 receptor antagonist HOE-140 inhibited bradykinin-induced membrane depolarizations. Furthermore, the cyclooxygenase inhibitor indomethacin attenuated bradykinin-induced membrane depolarizations to a similar magnitude (∼70%) as HOE-140. However, neurokinin-1 and -3 receptor antagonists did not have similar inhibitory effects. The ability of bradykinin to directly alter active properties of parasympathetic ganglion neurons was also examined. Bradykinin (100 nM) significantly reduced the duration of the afterhyperpolarization (AHP) that followed four consecutive action potentials. The inhibitory effect of bradykinin on the AHP response was reversed by HOE-140 but not by indomethacin. These results indicate that bradykinin can stimulate airway parasympathetic ganglion neurons independent of sensory nerve activation and provide an alternative mechanism for regulating airway parasympathetic tone.

scholarly journals Heterogeneity of Membrane Properties in Sympathetic Preganglionic Neurons of Neonatal Mice: Evidence of Four Subpopulations in the Intermediolateral Nucleus

2010 ◽  
Vol 103 (1) ◽  
pp. 490-498 ◽  
Author(s):  
Amanda Zimmerman ◽  
Shawn Hochman
Keyword(s):  
Time Constant ◽  
Cell Function ◽  
Input Resistance ◽  
Firing Frequency ◽  
Membrane Properties ◽  
Sympathetic Preganglionic Neurons ◽  
Preganglionic Neurons ◽  
Neonatal Mice ◽  
Potential Shape ◽  
Wide Range

Spinal cord sympathetic preganglionic neurons (SPNs) integrate activity from descending and sensory systems to determine the final central output of the sympathetic nervous system. The intermediolateral column (IML) has the highest number and density of SPNs and, within this region, SPN somas are found in distinct clusters within thoracic and upper lumbar spinal segments. Whereas SPNs exhibit a rostrocaudal gradient of end-target projections, individual clusters contain SPNs with diverse functional roles. Here we explored diversity in the electrophysiological properties observed in Hb9-eGFP–identified SPNs in the IML of neonatal mice. Overall, mouse SPN intrinsic membrane properties were comparable with those seen in other species. A wide range of values was obtained for all measured properties (up to a 10-fold difference), suggesting that IML neurons are highly differentiated. Using linear regression we found strong correlations between many cellular properties, including input resistance, rheobase, time constant, action potential shape, and degree of spike accommodation. The best predictor of cell function was rheobase, which correlated well with firing frequency–injected current ( f– I) slopes as well as other passive and active membrane properties. The range in rheobase suggests that IML neurons have a recruitment order with stronger synaptic drives required for maximal recruitment. Using cluster analysis, we identified at least four subpopulations of SPNs, including one with a long time constant, low rheobase, and high f– I gain. We thus propose that the IML contains populations of neurons that are differentiable by their membrane properties and hypothesize they represent diverse functional classes.

Electrotonic properties of neurons: steady-state compartmental model

1978 ◽  
Vol 41 (3) ◽  
pp. 621-639 ◽  
Author(s):  
D. H. Perkel ◽  
B. Mulloney
Keyword(s):  
Differential Equation ◽  
Steady State ◽  
Attenuation Factor ◽  
Dendritic Structure ◽  
Mathematical Expression ◽  
Input Resistance ◽  
Membrane Resistance ◽  
Degree Of Approximation ◽  
Matrix Differential ◽  
A Chain

1. If a neuron is represented by a network of resistively coupled isopotential regions, the passive flow of current in its dendritic structure and soma is described by a matrix differential equation. The matrix elements are defined in terms of membrane resistances and capacitances and of coupling resistances between adjoining regions. 2. A uniform cylidrical dendrite can be represented by a chain of identical regions. In this case, a closed-form mathematical expression is derived for the voltage attenuation factor of the dendrite at steady state in terms of the ratio of membrane resistance to coupling resistance. A numerical method is given to determine the coupling resistances, which in turn yield a specified attenuation factor. Related expressions are given for a dendrite coupled to a soma. Formulas are also derived for the input resistance in these configurations. 3. For more complicated neuronal structures, matrix manipulations are described which yield values for input resistances in all regions, attenuation factors between all pairs of regions, and values of applied voltages necessary to attain specified steady-state potentials. 4. Dynamic solutions to the differential equation provide voltage transients (PSPs). Comparison of the shape paramenters of these transients with those of experimental or cable-theoretical PSPs establishes the number of regions necessary to achieve a given degree of approximation to the transients predicted by cable theory.

Structural and functional alterations in rat corticospinal neurons after axotomy

1996 ◽  
Vol 75 (1) ◽  
pp. 248-267 ◽  
Author(s):  
G. F. Tseng ◽  
D. A. Prince
Keyword(s):  
Steady State ◽  
Cervical Spinal Cord ◽  
Input Resistance ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Survival Group ◽  
Double Labeling ◽  
Postsynaptic Potentials ◽  
Electrophysiological Properties

1. The electrophysiological properties of rat corticospinal neurons (CSNs) were studied 3, 9, and 12 mo after axotomy in the cervical spinal cord, with the use of a combination of the in vitro neocortical slice technique, intracellular recordings, and a double-labeling method that allowed identification of CSNs studied in vitro. 2. CSNs retained the rhodamine-labeled microspheres employed as a retrograde marker and were functionally active in the longest survival group (1 yr). 3. The somatic area of axotomized CSNs became progressively smaller, a reduction that amounted to 37% for all cells at 1 yr. There were no obvious differences between normal and axotomized cells in terms of apical dendritic widths, numbers of apical dendritic branches, or basal dendritic arbors. Intracortical axonal arborizations of axotomized neurons were in general similar to those of normal CSNs in that most axons ended in layers V and VI with only occasional collaterals reaching supragranular layers. 4. Axotomized CSNs were grouped according to their spike firing patterns during depolarizing current pulses so that their electrophysiological behavior could be compared with that of regular spiking and adapting groups of normal CSNs. No significant differences were found in resting membrane potential, or spike parameters between axotomized neurons in any survival group and normal controls. Neurons surviving 1 yr after axotomy had a higher input resistance (RN) than normal CSNs. There was a reduction in the percentage of CSNs that generated prominent spike depolarizing afterpotentials in the axotomized group. 5. The steady-state relationship between spike frequency and applied current (f-I slope) became steeper over time and was significantly greater 9 mo after axotomy in regular spiking (RS) and adapting neurons than in normal CSNs in the same groups. The increase in steady-state f-I slope was in part related to increases in the RN of axotomized neurons. 6. There was a significant decrease in the generation of slow afterhyperpolarizations following trains of spikes in axotomized versus normal RS neurons, first detected at 3 mo and also present in 9 mo and 1 yr survival groups. 7. Biphasic inhibitory postsynaptic potentials (IPSPs) were evoked in only 1 of 11 axotomized neurons in the 3-mo group, 2 of 12 cells examined at 9 mo, and 3 of 15 neurons 1 yr after axotomy. The proportions of neurons generating IPSPs were significantly smaller than in comparable groups of control CSNs. As a consequence, longer duration evoked excitatory postsynaptic potentials were generated by axotomized CSNs. 8. Results show that axotomized CSNs undergo alterations in intrinsic membrane properties and inhibitory synaptic electrogenesis that would tend to make them more responsive to excitatory inputs.

scholarly journals Multiple Effects of Serotonin on Membrane Properties of Trigeminal Motoneurons In Vitro

1997 ◽  
Vol 77 (6) ◽  
pp. 2910-2924 ◽  
Author(s):  
C. F. Hsiao ◽  
P. R. Trueblood ◽  
M. S. Levine ◽  
S. H. Chandler
Keyword(s):  
Steady State ◽  
Input Resistance ◽  
Membrane Properties ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Membrane Excitability ◽  
Maximum Slope ◽  
Inward Current ◽  
Trigeminal Motoneurons

Hsiao, C. F., P. R. Trueblood, M. S. Levine, and S. H. Chandler. Multiple effects of serotonin on membrane properties of trigeminal motoneurons in vitro. J. Neurophysiol. 77: 2910–2924, 1997. Intracellular recordings from guinea pig trigeminal motoneurons (TMNs) in brain stem slices were used to determine the underlying ionic mechanisms responsible for our previously demonstrated enhancement of TMN excitability during jaw movements by serotonin (5-HT). 5-HT (0.5–100 μM) depolarized motoneurons and increased input resistance in the majority of neurons tested. Additionally, 5-HT reduced the amplitude of the postspike medium-duration afterhyperpolarization, decreased the current threshold for maintained spike discharge, and increased the maximum slope of the steady-state spike frequency-current relationship. Under voltage clamp, from holding potentials close to resting potential, 5-HT produced an inward current and a decrease in instantaneous slope conductance, suggesting a reduction in a resting K+ leak conductance ( I leak). The instantaneous current-voltage ( I-V) relationship for the inward 5-HT current ( I 5-HT) was linear throughout most of the voltage range tested. However, the steady-state I-V relationship showed some degree of inward rectification at potentials starting around −70 mV. The mean reversal potential for the instantaneous I 5-HT was −86.2 ± 4.5 (SE) mV ( n = 9), a value slightly negative to the predicted potassium equilibrium potential of −82 mV in these neurons. In the presence of 2 mM Ba2+, 5-HT application did not produce a further reduction in input conductance, but did expose a Ba2+-insensitive residual inward current that was resistant to Cs+ application. The instantaneous I-V relationship during 5-HT application in the presence of Ba2+ was shifted downward and parallel to control, suggesting that Ba2+ and 5-HT block the same resting I leak. The residual Ba2+- and Cs+-insensitive component of the total inward I 5-HT was voltage independent and was blocked when the extracellular Na+ was replaced by choline, suggesting that the predominant charge carrier for this residual current is Na+. 5-HT enhanced a hyperpolarization-activated cationic current, I h. In the presence of Ba2+, the time course of I 5-HT resembled that of I h and showed a similar voltage dependence that was blocked by extracellular Cs+ (1–3 mM). The effects of 5-HT on membrane potential, input resistance, and I h were partially mimicked by 5-HT2 agonists and suppressed by 5-HT2 antagonists. It is concluded that 5-HT enhances TMN membrane excitability through modulation of multiple intrinsic membrane conductances. This provides for a mechanism(s) to fine tune the input-output discharge properties of these neurons, thus providing them with greater flexibility in output in response to time-varying synaptic inputs during various movements of the jaw.

Developmental Changes in Membrane Properties of Chemoreceptor Afferent Neurons of the Rat Petrosal Ganglia

1999 ◽  
Vol 82 (1) ◽  
pp. 209-215 ◽  
Author(s):  
David F. Donnelly
Keyword(s):  
Time Constant ◽  
Carotid Body ◽  
Action Potentials ◽  
Input Resistance ◽  
Developmental Changes ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Afferent Neurons ◽  
C Fibers ◽  
Ganglion Neurons

Carotid body chemoreceptors increase their responsiveness to hypoxia in the postnatal period, but the mechanism for this increase is unresolved. The purpose of the present study was to examine developmental changes in cellular characteristics of chemoreceptor afferent neurons in the petrosal ganglia with the underlying hypothesis that developmental changes occur and may account for the developmental increase in chemoreceptor responsiveness. Chemoreceptor complexes (carotid body, sinus nerve, glossopharyngeal nerve, and petrosal ganglia) were harvested from rats, aged 3–40 days, and intracellular recordings were obtained from petrosal ganglion neurons using sharp electrode impalement. All chemoreceptor neurons across ages were C fibers with conduction velocities <1 m/s and generated repetitive action potentials with depolarization. Resting membrane potential was −61.3 ± 0.9 (SE) mV ( n = 78) and input resistance was 108 ± 6 MΩ and did not significantly change with age. Cell capacitance was 32.4 ± 1.7 pF and did not change with age. Rheobase averaged 0.21 ± 0.02 nA and slightly increased with age. Action potentials were followed by an afterhyperpolarization of 12.4 ± 0.6 mV and time constant 6.9 ± 0.5 ms; only the time constant decreased with age. These results, obtained in rat, demonstrate electrophysiologic characteristics which differ substantially from that previously described in cat chemoreceptor neurons. In general developmental changes in cell characteristics are small and are unlikely to account for the developmental increase in chemoreceptor responsiveness with age.

scholarly journals Cholinergic Responses and Intrinsic Membrane Properties of Developing Thalamic Parafascicular Neurons

2009 ◽  
Vol 102 (2) ◽  
pp. 774-785 ◽  
Author(s):  
Meijun Ye ◽  
Abdallah Hayar ◽  
Edgar Garcia-Rill
Keyword(s):  
Action Potential ◽  
Time Constant ◽  
Rem Sleep ◽  
Input Resistance ◽  
Pedunculopontine Nucleus ◽  
Inhibitory Response ◽  
Half Width ◽  
Membrane Properties ◽  
Cholinergic Antagonists ◽  
Duration Of Action

Parafascicular (Pf) neurons receive cholinergic input from the pedunculopontine nucleus (PPN), which is active during waking and REM sleep. There is a developmental decrease in REM sleep in humans between birth and puberty and 10–30 days in rat. Previous studies have established an increase in muscarinic and 5-HT1 serotonergic receptor–mediated inhibition and a transition from excitatory to inhibitory GABAA responses in the PPN during the developmental decrease in REM sleep. However, no studies have been conducted on the responses of Pf cells to the cholinergic input from the PPN during development, which is a major target of ascending cholinergic projections and may be an important mechanism for the generation of rhythmic oscillations in the cortex. Whole cell patch-clamp recordings were performed in 9- to 20-day-old rat Pf neurons in parasagittal slices, and responses to the cholinergic agonist carbachol (CAR) were determined. Three types of responses were identified: inhibitory (55.3%), excitatory (31.1%), and biphasic (fast inhibitory followed by slow excitatory, 6.8%), whereas 6.8% of cells showed no response. The proportion of CAR-inhibited Pf neurons increased with development. Experiments using cholinergic antagonists showed that M2 receptors mediated the inhibitory response, whereas excitatory modulation involved M1, nicotinic, and probably M3 or M5 receptors, and the biphasic response was caused by the activation of multiple types of muscarinic receptors. Compared with CAR-inhibited cells, CAR-excited Pf cells showed 1) a decreased membrane time constant, 2) higher density of hyperpolarization-activated channels ( Ih), 3) lower input resistance ( Rin), 4) lower action potential threshold, and 5) shorter half-width duration of action potentials. Some Pf cells exhibited spikelets, and all were excited by CAR. During development, we observed decreases in Ih density, Rin, time constant, and action potential half-width. These results suggest that cholinergic modulation of Pf differentially affects separate populations, perhaps including electrically coupled cells. Pf cells tend to show decreased excitability and cholinergic activation during the developmental decrease in REM sleep.

Differential Thermosensitivity of Sensory Neurons in the Guinea Pig Trigeminal Ganglion

2003 ◽  
Vol 90 (4) ◽  
pp. 2219-2231 ◽  
Author(s):  
C. Cabanes ◽  
F. Viana ◽  
C. Belmonte
Keyword(s):  
Guinea Pig ◽  
Sensory Neurons ◽  
Trigeminal Ganglion ◽  
Input Resistance ◽  
Membrane Properties ◽  
Cold Sensitivity ◽  
Inward Rectification ◽  
Nerve Terminals ◽  
Membrane Hyperpolarization

Intracellular recordings were employed to study the effects of temperature on membrane properties and excitability in sensory neurons of the intact guinea pig trigeminal ganglion (TG) maintained in vitro. Neurons were classified according to the shape and duration of the action potential into F (short-duration, fast spike) and S (long duration, slow spike with a “hump”) types. Most type F (33/34) neurons had axons with conduction velocities >1.5 m/s, while only 30% (6/23) of type S neurons reached these conduction speeds suggesting differences in myelination. Cooling reduced axonal conduction velocity and prolonged spike duration in both neuronal types. In F-type neurons with strong inward rectification. cooling also increased the excitability, augmenting the input resistance and reducing the current firing threshold. These effects were not observed in S-type neurons lacking inward rectification. In striking contrast to results obtained in cultured TG neurons, cooling or menthol did not induce firing in recordings from the acutely isolated ganglion. However, after application of submillimolar concentrations (100 μM) of the potassium channel blocker 4-aminopyridine (4-AP), 29% previously unresponsive neurons developed cold sensitivity. An additional 31% developed ongoing activity that was sensitive to temperature. Only neurons with strong inward rectification (mostly F-type) became thermosensitive. Cooling- and 4-AP–evoked firing were insensitive to intracellular application of 4-AP or somatic membrane hyperpolarization, suggesting that their action was most prominent at the level of the axon. The lack of excitatory actions of low temperature in the excised intact ganglion contrasts with the impulse discharges induced by cooling in trigeminal nerve terminals of the same species, suggesting a critical difference between cold-transduction mechanisms at the level of the nerve terminals and the soma.

Nonuniform passive membrane properties of rat lumbar sympathetic ganglion cells

1987 ◽  
Vol 57 (3) ◽  
pp. 633-644 ◽  
Author(s):  
S. J. Redman ◽  
E. M. McLachlan ◽  
G. D. Hirst
Keyword(s):  
Time Constant ◽  
Sympathetic Neurons ◽  
Potassium Conductance ◽  
Membrane Conductance ◽  
Input Resistance ◽  
Membrane Properties ◽  
Voltage Response ◽  
Bathing Solution ◽  
Passive Membrane Properties ◽  
Passive Membrane

We have studied the passive membrane properties of sympathetic neurons in isolated lumbar paravertebral ganglia of young rats by recording the voltage response to small steps of current passed through an intracellular microelectrode. Substitution of Ba2+ (2.5 mM) for Ca2+ (2.5 mM) in the bathing solution increased the input resistance and the time constant of the voltage response, but the increase in time constant was disproportionately large relative to the increase in input resistance. After consideration of the passive electrical properties and the geometry of the soma and dendrites, it was concluded that the disproportionate change in input resistance and time constant could be explained if barium inactivated a resting potassium conductance that was concentrated in the distal dendrites. In the APPENDIX, the effect of nonuniform membrane conductance on the relationship between input resistance and time constant in models of these neurons is analyzed.

Properties of visceral primary afferent neurons in the nodose ganglion of the rabbit

1985 ◽  
Vol 54 (2) ◽  
pp. 245-260 ◽  
Author(s):  
C. E. Stansfeld ◽  
D. I. Wallis
Keyword(s):  
Action Potentials ◽  
Input Resistance ◽  
Nodose Ganglion ◽  
Time Dependent ◽  
Membrane Properties ◽  
Resting Potential ◽  
Inward Rectification ◽  
C Cells ◽  
Axonal Conduction ◽  
A Cells

The active and passive membrane properties of rabbit nodose ganglion cells and their responsiveness to depolarizing agents have been examined in vitro. Neurons with an axonal conduction velocity of less than 3 m/s were classified as C-cells and the remainder as A-cells. Mean axonal conduction velocities of A- and C-cells were 16.4 m/s and 0.99 m/s, respectively. A-cells had action potentials of brief duration (1.16 ms), high rate of rise (385 V/s), an overshoot of 23 mV, and relatively high spike following frequency (SFF). C-cells typically had action potentials with a "humped" configuration (duration 2.51 ms), lower rate of rise (255 V/s), an overshoot of 28.6 mV, an after potential of longer duration than A-cells, and relatively low SFF. Eight of 15 A-cells whose axons conducted at less than 10 m/s had action potentials of longer duration with a humped configuration; these were termed Ah-cells. They formed about 10% of cells whose axons conducted above 2.5 m/s. The soma action potential of A-cells was blocked by tetrodotoxin (TTX), but that of 6/11 C-cells was unaffected by TTX. Typically, A-cells showed strong delayed (outward) rectification on passage of depolarizing current through the soma membrane and time-dependent (inward) rectification on inward current passage. Input resistance was thus highly sensitive to membrane potential close to rest. In C-cells, delayed rectification was not marked, and slight time-dependent rectification occurred in only 3 of 25 cells; I/V curves were normally linear over the range: resting potential to 40 mV more negative. Data on Ah-cells were incomplete, but in our sample of eight cells time-dependent rectification was absent or mild. C-cells had a higher input resistance and a higher neuronal capacitance than A-cells. In a proportion of A-cells, RN was low at resting potential (5 M omega) but increased as the membrane was hyperpolarized by a few millivolts. A-cells were depolarized by GABA but were normally unaffected by 5-HT or DMPP. C-cells were depolarized by GABA in a similar manner to A-cells but also responded strongly to 5-HT; 53/66 gave a depolarizing response, and 3/66, a hyperpolarizing response. Of C-cells, 75% gave a depolarizing response to DMPP.(ABSTRACT TRUNCATED AT 400 WORDS)

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