In vitro characterization of neurons in the ventral part of the nucleus tractus solitarius. I. Identification of neuronal types and repetitive firing properties

1987 ◽  
Vol 58 (1) ◽  
pp. 195-214 ◽  
Author(s):  
M. S. Dekin ◽  
P. A. Getting ◽  
S. M. Johnson
Keyword(s):  
High Frequency ◽  
Nucleus Tractus Solitarius ◽  
State Level ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Steady State Level ◽  
Shaped Cell ◽  
Firing Properties

1. An in vitro brain stem slice preparation from adult guinea pigs was used to determine the properties of neurons located in the ventral part of the nucleus tractus solitarius (NTS), an area associated with the dorsal respiratory group. Based upon their morphology and their repetitive firing properties, three classes of ventral NTS neurons, termed types I, II, and III, were observed. 2. Type I neurons were multipolar with pyramidal-shaped cell bodies. These neurons responded to prolonged depolarizations from a resting level of -50 mV with a discrete, high-frequency burst of spikes, which rapidly adapted to a low steady-state level. When depolarized from levels more negative than -65 mV, the initial burst was diminished. 3. Type II neurons were multipolar with fusiform-shaped cell bodies. Type II neurons responded to depolarizations from -50 mV with an initial high spike frequency, which gradually adapted to a steady-state level. When depolarized from levels more negative than -60 mV, these neurons displayed a delay between the onset of the stimulus and the first spike. This delay has been termed “delayed excitation.” The expression of delayed excitation was modulated by both the size and duration of hyperpolarizing prepulses that preceded depolarization. 4. Type III neurons were multipolar with spherical shaped-cell bodies. In response to depolarizations from -50 mV, these neurons displayed high-frequency firing with little adaptation. The repetitive firing properties of type III neurons were not modulated by hyperpolarization. 5. Bulbospinal neurons in the ventral NTS were identified using retrograde transport of rhodamine-labeled latex beads injected into the region of the phrenic motor nucleus at spinal cord levels C4 through C6. Only type I and type II neurons were labeled in the ventral NTS (0.2-1.0 mm rostral to the obex). Both contralateral and ipsilateral projections were observed. Contralaterally, type I and II neurons were evenly distributed. Ipsilaterally, however, type II neurons accounted for two-thirds of the labeled neurons. 6. Type I and II neurons had similar input resistances and time constants: 97.0 +/- 17.6 M omega and 14.4 +/- 2.2 ms (n = 5) for type I and 107.0 +/- 11.2 M omega and 13.7 +/- 1.6 ms for type II (n = 5).(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro characterization of neurons in the ventral part of the nucleus tractus solitarius. II. Ionic basis for repetitive firing patterns

1987 ◽  
Vol 58 (1) ◽  
pp. 215-229 ◽  
Author(s):  
M. S. Dekin ◽  
P. A. Getting
Keyword(s):  
Potassium Current ◽  
Voltage Dependence ◽  
Nucleus Tractus Solitarius ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Ventral Part ◽  
Firing Properties ◽  
Ionic Basis

1. The ventral part of the nucleus tractus solitarius in guinea pigs comprises the dorsal respiratory group and is composed of three classes of neurons. These have been termed types I, II, and III. Each cell type possesses a unique set of repetitive firing properties. An in vitro brain stem slice preparation was used to study the ionic basis for these repetitive firing properties. 2. Three different membrane currents were shown to contribute to the repetitive firing properties. These were: a slow calcium current (ICa), an early, transient potassium current (IKA), and a calcium-activated potassium current (IKC). Type I and II neurons displayed physiologically significant amounts of these currents; type III neurons did not. 3. During depolarization from potential levels between -50 and -60 mV, the repetitive firing properties of type I and II neurons were determined primarily by ICa and IKC. IKA was inactivated in this potential range. The expression of IKC was greater in type I neurons than in type II neurons, and as a result, type I neurons exhibited a self-terminating burst of spike activity early in depolarization, whereas type II neurons displayed a gradual decline in spike frequency throughout depolarization. 4. The properties of IKA in type I and II neurons were studied using the single-electrode voltage-clamp technique. The kinetics of IKA in type I neurons was approximately twice as slow as those of type II neurons. In addition, the voltage dependence of activation and the removal of inactivation for IKA in type I neurons were shifted by about -10 mV with respect to type II neurons. 5. Depolarization of type I neurons from membrane potential levels where inactivation of IKA was removed caused a decrease in the frequency of the initial burst of spikes. This decrease in spike frequency was result of the coactivation of IKA with ICa. 6. Depolarization of type II neurons from membrane potentials where inactivation of IKA was removed caused a long delay between the onset of depolarization and the beginning of spike activity. The delay in excitation was modulated by both the magnitude and duration of the prestimulus hyperpolarization. This modulation of delayed excitation paralleled the time and voltage dependence for the removal of IKA inactivation in type II neurons.

Characteristic Membrane Potential Trajectories in Primate Sensorimotor Cortex Neurons Recorded In Vivo

2005 ◽  
Vol 94 (4) ◽  
pp. 2713-2725 ◽  
Author(s):  
Daofen Chen ◽  
Eberhard E. Fetz
Keyword(s):  
Membrane Potential ◽  
Sensorimotor Cortex ◽  
High Frequency ◽  
Cortical Neurons ◽  
Type I ◽  
Type Ii ◽  
Interspike Intervals ◽  
Cortical Oscillations ◽  
Firing Properties

We examined the membrane potentials and firing properties of motor cortical neurons recorded intracellularly in awake, behaving primates. Three classes of neuron were distinguished by 1) the width of their spikes, 2) the shape of the afterhyperpolarization (AHP), and 3) the distribution of interspike intervals. Type I neurons had wide spikes, exhibited scoop-shaped AHPs, and fired irregularly. Type II neurons had narrower spikes, showed brief postspike afterdepolarizations before the AHP, and sometimes fired high-frequency doublets. Type III neurons had the narrowest spikes, showed a distinct post-AHP depolarization, or “rebound AHP” (rAHP), lasting nearly 30 ms, and tended to fire at 25–35 Hz. The evidence suggests that an intrinsic rAHP may confer on these neurons a tendency to fire at a preferred frequency governed by the duration of the rAHP and may contribute to a “pacemaking” role in generating cortical oscillations.

Inward rectification and its effects on the repetitive firing properties of bulbospinal neurons located in the ventral part of the nucleus tractus solitarius

1993 ◽  
Vol 70 (2) ◽  
pp. 590-601 ◽  
Author(s):  
M. S. Dekin
Keyword(s):  
Membrane Potential ◽  
Nucleus Tractus Solitarius ◽  
Reversal Potential ◽  
Repetitive Firing ◽  
Inward Rectification ◽  
Motor Nucleus ◽  
Type I ◽  
Type Ii ◽  
Membrane Hyperpolarization ◽  
Negative Current

1. An in vitro brain stem slice from adult guinea pigs was used to study the effects of membrane hyperpolarization in two classes of bulbospinal neurons, called types I and II, from the ventral parts of the nucleus tractus solitarius (vNTS). These bulbospinal neurons project to the phrenic motor nucleus and make up the dorsal respiratory group, a sensorimotor integrating area for rhythmic breathing movements. 2. Negative current injections (1 s long) were used in the discontinuous current-clamp mode to study the input resistance (Rin) in both classes of bulbospinal vNTS neurons. The mean Rin for type I neurons was 88.7 +/- 13.8 (SD) M omega (n = 19) and for type II neurons was 92.6 +/- 14.0 M omega (n = 16). Both classes of neurons displayed a depolarizing sag and inward rectification during negative current injections to membrane-potential levels less than or equal to -70 mV. The magnitude of the depolarizing sag became larger as the size of the negative current step was increased. On release from hyperpolarization, both cell types also exhibited a large anode break hyperpolarization (ABH). 3. The ABH was abolished in the presence of 5 mM 4-amino-pyridine (4-AP), whereas the depolarizing sag and inward rectification were not affected. In the place of the ABH, a small postinhibitory rebound (PIR) depolarization was observed on release from hyperpolarization. The magnitude of PIR was dependent on the size of the depolarizing sag. In the presence of both 5 mM 4-AP and 5 mM Cs+, the depolarizing sag and PIR were completely blocked, whereas Rin was increased. 4. The ionic currents underlying the ABH and depolarizing sag were directly observed by the use of the discontinuous single-electrode voltage-clamp technique. The ABH was caused by activation of an A-current (IKA). The depolarizing sag was associated with a hyperpolarization-activated inward current (IH), which was activated at membrane-potential levels less than or equal to -70 mV. The peak amplitude of IH in type I neurons was -335 +/- 16 pA (n = 13) and in type II cells was -327 +/- 14 pA (n = 11). 5. IH currents did not display inactivation during the hyperpolarizing voltage step. The IH current became larger when [K+]o was increased from 4 mM (control) to 12 mM and was blocked in the presence of 5 mM Cs+. The estimated reversal potential for the IH current was -41.5 +/- 4.8 mV (n = 8).(ABSTRACT TRUNCATED AT 400 WORDS)

Modeling Endoleaks and Collateral Reperfusion following Endovascular AAA Exclusion

2003 ◽  
Vol 10 (3) ◽  
pp. 424-432 ◽  
Author(s):  
Chuh K. Chong ◽  
Thien V. How ◽  
Geoffrey L. Gilling-Smith ◽  
Peter L. Harris
Keyword(s):  
Stent Graft ◽  
Aortic Pressure ◽  
Type I ◽  
Type Ii ◽  
Pump System ◽  
Type Ii Endoleak ◽  
Type I Endoleak ◽  
The Impact ◽  
Mean Aortic Pressure

Purpose: To investigate the effect on intrasac pressure of stent-graft deployment within a life-size silicone rubber model of an abdominal aortic aneurysm (AAA) maintained under physiological conditions of pressure and flow. Methods: A commercial bifurcated device with the polyester fabric preclotted with gelatin was deployed in the AAA model. A pump system generated physiological flow. Mean and pulse aortic and intrasac pressures were measured simultaneously using pressure transducers. To simulate a type I endoleak, plastic tubing was placed between the aortic wall and the stent-graft at the proximal anchoring site. Type II endoleak was simulated by means of side branches with set inflow and outflow pressures and perfusion rates. Type IV endoleak was replicated by removal of gelatin from the graft fabric. Results: With no endoleak, the coated graft reduced the mean and pulse sac pressures to negligible values. When a type I endoleak was present, mean sac pressure reached a value similar to mean aortic pressure. When net flow through the sac due to a type II endoleak was present, mean sac pressure was a function of the inlet pressure, while pulse pressure in the sac was dependent on both inlet and outlet pressures. As perfusion rates increased, both mean and pulse sac pressures decreased. When there was no outflow, mean sac pressure was similar to mean aortic pressure. In the presence of both type I and type II endoleaks, mean sac pressure reached mean aortic pressure when the net perfusion rate was low. Conclusions: In vitro studies are useful in gaining an understanding of the impact of different types of endoleaks, in isolation and in combination, on intrasac pressure after aortic stent-graft deployment.

Type VI collagen expression is upregulated in the early events of chondrocyte differentiation

Development ◽  
1993 ◽  
Vol 117 (1) ◽  
pp. 245-251
Author(s):  
R. Quarto ◽  
B. Dozin ◽  
P. Bonaldo ◽  
R. Cancedda ◽  
A. Colombatti
Keyword(s):  
Suspension Culture ◽  
Type I Collagen ◽  
Type Ii Collagen ◽  
Type I ◽  
Type Ii ◽  
Type Vi Collagen ◽  
Full Spectrum ◽  
Collagen Expression ◽  
Hypertrophic Chondrocyte

Dedifferentiated chondrocytes cultured adherent to the substratum proliferate and synthesize large amounts of type I collagen but when transferred to suspension culture they decrease proliferation, resume the chondrogenic phenotype and the synthesis of type II collagen, and continue their maturation to hypertrophic chondrocyte (Castagnola et al., 1986, J. Cell Biol. 102, 2310–2317). In this report, we describe the developmentally regulated expression of type VI collagen in vitro in differentiating avian chondrocytes. Type VI collagen mRNA is barely detectable in dedifferentiated chondrocytes as long as the attachment to the substratum is maintained, but increases very rapidly upon passage of the cells into suspension culture reaching a peak after 48 hours and declining after 5–6 days of suspension culture. The first evidence of a rise in the mRNA steady-state levels is obtained already at 6 hours for the alpha 3(VI) chain. Immunoprecipitation of metabolically labeled cells with type VI collagen antibodies reveals that the early mRNA rise is paralleled by an increased secretion of type VI collagen in cell media. Induction of type VI collagen is not the consequence of trypsin treatment of dedifferentiated cells since exposure to the actin-disrupting drug cytochalasin or detachment of the cells by mechanical procedures has similar effects. In 13-day-old chicken embryo tibiae, where the full spectrum of the chondrogenic differentiation process is represented, expression of type VI collagen is restricted to the articular cartilage where chondrocytes developmental stage is comparable to stage I (high levels of type II collagen expression).(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital Dyserythropoietic Anemia

PEDIATRICS ◽  
1973 ◽  
Vol 51 (5) ◽  
pp. 957-958
Author(s):  
G. Bennett Humphrey ◽  
Bahaod-Din Mojab ◽  
Ingomar Mutz
Keyword(s):  
Carbohydrate Metabolism ◽  
Morphological Characteristics ◽  
Type I ◽  
Type Ii ◽  
Congenital Dyserythropoietic Anemia ◽  
The 1950S ◽  
Deja Vu ◽  
Déjà Vu ◽  
Excellent Article

Reading the excellent article by Drs. Murphy and Oski, "Congenital Dyserythropoietic Anemia (CDA)",1 which further defines type II, produced a sense of deja vu. In the 1950s, nonspherocytic, hemolytic anemias (HNHA) were categorized as type I and II based on the in vitro autohemolysis test.2 This group of anemias has subsequently been demonstrated to be due to a series of enzymatic abnormalities in carbohydrate metabolism.3 In CDA, the morphological characteristics which define types I, II, and III probably reflect nuclear rather than cytoplasmic abnormalities.

Electrophysiology of globus pallidus neurons in vitro

1994 ◽  
Vol 72 (3) ◽  
pp. 1127-1139 ◽  
Author(s):  
A. Nambu ◽  
R. Llinas
Keyword(s):  
Globus Pallidus ◽  
Input Resistance ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Low Threshold ◽  
Membrane Oscillations ◽  
Neuronal Type ◽  
A Current ◽  
Membrane Level

1. We investigated the electrical properties of globus pallidus neurons intracellularly using brain slices from adult guinea pigs. Three types of neurons were identified according to their intrinsic electrophysiological properties. 2. Type I neurons (59%) were silent at the resting membrane level (-65 +/- 10 mV, mean +/- SD) and generated a burst of spikes, with strong accommodation, to depolarizing current injection. Calcium-dependent low-frequency (1-8 Hz) membrane oscillations were often elicited by membrane depolarization (-53 +/- 8 mV). A low-threshold calcium conductance and an A-current were also identified. The mean input resistance of this neuronal type was 70 +/- 22 M omega. 3. Type II neurons (37%) fired spontaneously at the resting membrane level (-59 +/- 9 mV). Their repetitive firing (< or = 200 Hz) was very sensitive to the amplitude of injected current and showed weak accommodation. Sodium-dependent high-frequency (20-100 Hz) subthreshold membrane oscillations were often elicited by membrane depolarization. This neuronal type demonstrated a low-threshold calcium spike and had the highest input resistance (134 +/- 62 M omega) of the three neuron types. 4. Type III neurons (4%) did not fire spontaneously at the resting membrane level (-73 +/- 5 mV). Their action potentials were characterized by a long duration (2.3 +/- 0.6 ms). Repetitive firing elicited by depolarizing current injection showed weak or no accommodation. This neuronal type had an A-current and showed the lowest input resistance (52 +/- 35 M omega) of the three neuron types. 5. Stimulation of the caudoputamen evoked inhibitory postsynaptic potentials (IPSPs) in Type I and II neurons. In Type II neurons the IPSPs were usually followed by rebound firing. Excitatory postsynaptic potentials and antidromic responses were also elicited in some Type I and II neurons. The estimated conduction velocity of the striopallidal projection was < 1 m/s (Type I neurons, 0.49 +/- 0.37 m/s; Type II neurons, 0.33 +/- 0.13 m/s).

The Roles Potassium Currents Play in Regulating the Electrical Activity of Ventral Cochlear Nucleus Neurons

2003 ◽  
Vol 89 (6) ◽  
pp. 3097-3113 ◽  
Author(s):  
Jason S. Rothman ◽  
Paul B. Manis
Keyword(s):  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Threshold Current ◽  
Repetitive Firing ◽  
Resting Membrane Potential ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Ventral Cochlear Nucleus ◽  
Discharge Patterns

Using kinetic data from three different K+ currents in acutely isolated neurons, a single electrical compartment representing the soma of a ventral cochlear nucleus (VCN) neuron was created. The K+ currents include a fast transient current ( IA), a slow-inactivating low-threshold current ( ILT), and a noninactivating high-threshold current ( IHT). The model also includes a fast-inactivating Na+ current, a hyperpolarization-activated cation current ( Ih), and 1–50 auditory nerve synapses. With this model, the role IA, ILT, and IHT play in shaping the discharge patterns of VCN cells is explored. Simulation results indicate that IHT mainly functions to repolarize the membrane during an action potential, and IA functions to modulate the rate of repetitive firing. ILT is found to be responsible for the phasic discharge pattern observed in Type II cells (bushy cells). However, by adjusting the strength of ILT, both phasic and regular discharge patterns are observed, demonstrating that a critical level of ILT is necessary to produce the Type II response. Simulated Type II cells have a significantly faster membrane time constant in comparison to Type I cells (stellate cells) and are therefore better suited to preserve temporal information in their auditory nerve inputs by acting as precise coincidence detectors and having a short refractory period. Finally, we demonstrate that modulation of Ih, which changes the resting membrane potential, is a more effective means of modulating the activation level of ILT than simply modulating ILT itself. This result may explain why ILT and Ih are often coexpressed throughout the nervous system.

Disparate cytokine regulation of ICAM-1 in rat alveolar epithelial cells and pulmonary endothelial cells in vitro

1995 ◽  
Vol 269 (1) ◽  
pp. L127-L135 ◽  
Author(s):  
W. W. Barton ◽  
S. Wilcoxen ◽  
P. J. Christensen ◽  
R. Paine
Keyword(s):  
Endothelial Cells ◽  
Epithelial Cells ◽  
Inflammatory Cytokines ◽  
Alveolar Epithelial Cells ◽  
Normal Lung ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Alveolar Epithelial

Intercellular adhesion molecule-1 (ICAM-1) is expressed at high levels on type I alveolar epithelial cells in the normal lung and is induced in vitro as type II cells spread in primary culture. In contrast, in most nonhematopoetic cells ICAM-1 expression is induced in response to inflammatory cytokines. We have formed the hypothesis that the signals that control ICAM-1 expression in alveolar epithelial cells are fundamentally different from those controlling expression in most other cells. To test this hypothesis, we have investigated the influence of inflammatory cytokines on ICAM-1 expression in isolated type II cells that have spread in culture and compared this response to that of rat pulmonary artery endothelial cells (RPAEC). ICAM-1 protein, determined both by a cell-based enzyme-linked immunosorbent assay and by Western blot analysis, and mRNA were minimally expressed in unstimulated RPAEC but were significantly induced in a time- and dose-dependent manner by treatment with tumor necrosis factor-alpha, interleukin-1 beta, or interferon-gamma. In contrast, these cytokines did not influence the constitutive high level ICAM-1 protein expression in alveolar epithelial cells and only minimally affected steady-state mRNA levels. ICAM-1 mRNA half-life, measured in the presence of actinomycin D, was relatively long at 7 h in alveolar epithelial cells and 4 h in RPAEC. The striking lack of response of ICAM-1 expression by alveolar epithelial cells to inflammatory cytokines is in contrast to virtually all other epithelial cells studied to date and supports the hypothesis that ICAM-1 expression by these cells is a function of cellular differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Common Anesthetics on Dendritic Properties in Layer 5 Neocortical Pyramidal Neurons

2008 ◽  
Vol 99 (3) ◽  
pp. 1394-1407 ◽  
Author(s):  
Sarah Potez ◽  
Matthew E. Larkum
Keyword(s):  
High Frequency ◽  
Pyramidal Neurons ◽  
Animal Experiments ◽  
Apical Dendrite ◽  
Network Activity ◽  
Calcium Spikes ◽  
Firing Properties ◽  
The Impact

Understanding the impact of active dendritic properties on network activity in vivo has so far been restricted to studies in anesthetized animals. However, to date no study has been made to determine the direct effect of the anesthetics themselves on dendritic properties. Here, we investigated the effects of three types of anesthetics commonly used for animal experiments (urethane, pentobarbital and ketamine/xylazine). We investigated the generation of calcium spikes, the propagation of action potentials (APs) along the apical dendrite and the somatic firing properties in the presence of anesthetics in vitro using dual somatodendritic whole cell recordings. Calcium spikes were evoked with dendritic current injection and high-frequency trains of APs at the soma. Surprisingly, we found that the direct actions of anesthetics on calcium spikes were very different. Two anesthetics (urethane and pentobarbital) suppressed dendritic calcium spikes in vitro, whereas a mixture of ketamine and xylazine enhanced them. Propagation of spikes along the dendrite was not significantly affected by any of the anesthetics but there were various changes in somatic firing properties that were highly dependent on the anesthetic. Last, we examined the effects of anesthetics on calcium spike initiation and duration in vivo using high-frequency trains of APs generated at the cell body. We found the same anesthetic-dependent direct effects in addition to an overall reduction in dendritic excitability in anesthetized rats with all three anesthetics compared with the slice preparation.

Sign in / Sign up

Export Citation Format

Share Document