Connectivity of slowly adapting pulmonary stretch receptors with dorsal medullary respiratory neurons

1987 ◽  
Vol 58 (6) ◽  
pp. 1259-1274 ◽  
Author(s):  
A. J. Berger ◽  
T. E. Dick
Keyword(s):  
Electrical Stimulation ◽  
Membrane Potential ◽  
Beta Cells ◽  
Spike Activity ◽  
Alpha Cells ◽  
Drg Neurons ◽  
Lung Inflation ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
P Cells

1. Intracellular recordings were made from 50 dorsal respiratory group (DRG) neurons in the region of the ventrolateral nucleus of the solitary tract in anesthetized, paralyzed cats ventilated with a cycle-triggered pump whose inflation stroke was triggered by the onset of phrenic nerve inspiratory (I) discharge. Activity was recorded simultaneously in the ipsilateral nodose ganglion from sensory cell bodies of slowly adapting pulmonary stretch receptors (PSRs). 2. Respiratory cycle-related membrane potential changes of DRG neurons were recorded. Twenty-six neurons that did not exhibit spikes were classified as I alpha, I beta or pump (P)-cells by comparing their membrane potential trajectories during I in the presence of lung inflation with that observed during I, but with lung inflation withheld. The remaining 24 neurons were classified similarly, but the classification was based upon a comparison of their I-phase spike activity responses with and without lung inflation. I phase-related histograms of either membrane potential or spike activity were constructed to facilitate DRG neuronal classification. Additionally, steady lung inflation of varying magnitudes was applied during the expiratory phase. This prolonged expiration and produced different responses in the neurons. Generally, I beta and P-cells were depolarized, whereas I alpha cells were hyperpolarized. 3. Low-intensity electrical stimulation of the ipsilateral vagus nerve evoked excitatory postsynaptic potentials (EPSPs) in all three DRG neuronal types. P-cells and I beta cells exhibited EPSPs in response to the lowest intensity; generally this intensity was below threshold for the simultaneously recorded PSR. Overall, EPSPs in I alpha cells had the highest thresholds, but some EPSPs could be evoked at thresholds similar to those of the I beta cells. The distributions of the average onset latency of the evoked EPSP overlapped considerably. Thus vagal electrical stimulation cannot be used for unequivocal classification of DRG neurons into I alpha, I beta, and P-cell subpopulations. 4. Using intracellular spike-triggered averaging, single PSRs were shown to generate monosynaptic EPSPs in I beta neurons and P-cells but not I alpha cells. Divergence of single PSR afferents also was observed. Relationships between EPSP shape factors, amplitudes, and PSR afferent conduction velocity are similar to those previously observed for monosynaptic EPSPs in hindlimb motoneurons generated by spinal afferents.

Monosynaptic excitation of dorsal medullary respiratory neurons by slowly adapting pulmonary stretch receptors

1984 ◽  
Vol 52 (4) ◽  
pp. 771-785 ◽  
Author(s):  
D. B. Averill ◽  
W. E. Cameron ◽  
A. J. Berger
Keyword(s):  
Respiratory Neurons ◽  
Drg Neurons ◽  
K Value ◽  
Lung Inflation ◽  
Medullary Respiratory Neurons ◽  
Dorsal Respiratory Group ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
The Cross ◽  
P Cells

The discharges of individual slowly adapting pulmonary stretch receptors (PSRs) and single respiratory neurons of the dorsal respiratory group (DRG) within the ventrolateral subnucleus of the solitary tract were recorded simultaneously in anesthetized, paralyzed, artificially ventilated cats. DRG neurons were classified as P-cell, I-alpha, or I-beta, based on the alteration in activity during respiratory cycles when lung inflation was withheld compared to activity when the lungs were inflated in phase with central inspiratory drive. In some cases, vagal stimulation was also used to classify respiratory neurons. Synaptic input of PSRs onto DRG neurons was examined by the construction of cross-correlograms for the simultaneously recorded discharge of individual PSRs (reference events) and individual DRG neurons (correlated events). Monosynaptic excitatory connections were demonstrated by peaks in 26% of the cross-correlograms of PSR and P-cell pairs and 20% of the cross-correlograms of PSR and I-beta neuron pairs. The ratio of the peak number of occurrences to the background number of occurrences (k value) was comparable for P-cells and I-beta neurons: 2.96 +/- 2.09 and 1.62 +/- 0.36 (mean +/- SD), respectively. P-cells and I-beta neurons also had similar short latencies for the peak of increased probability of discharge: 2.74 +/- 0.53 and 2.57 +/- 0.63 ms, respectively. No evidence was obtained demonstrating synaptic connectivity between PSRs and I-alpha neurons. Interpretations of this negative result are discussed.

Effect of central CO2 drive on lung inflation responses of expiratory bulbospinal neurons in dogs

2000 ◽  
Vol 279 (5) ◽  
pp. R1606-R1618 ◽  
Author(s):  
Mislav Tonkovic-Capin ◽  
Edward J. Zuperku ◽  
Eckehard A. Stuth ◽  
Jurica Bajic ◽  
Zoran Dogas ◽  
...  
Keyword(s):  
Empirical Model ◽  
Time Course ◽  
Transpulmonary Pressure ◽  
Neuronal Responses ◽  
Lung Inflation ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Thiopental Sodium ◽  
Inhibitory Components ◽  
Discharge Patterns

The purpose of these studies is to better understand the nature of the reflex interactions that control the discharge patterns of caudal medullary, expiratory (E) bulbospinal neurons. We examined the effect of central chemodrive inputs measured as arterial CO2 tension (PaCO2 ) during hyperoxia on the excitatory and inhibitory components of the lung inflation responses of these neurons in thiopental sodium-anesthetized, paralyzed dogs. Data from slow ramp inflation and deflation test patterns, which were separated by several control inflation cycles, were used to produce plots of neuronal discharge frequency ( F n) versus transpulmonary pressure (Pt). Pt was used as an index of the activity arising from the slowly adapting pulmonary stretch receptors (PSRs). Changes in inspired CO2 concentrations were used to produce PaCO2 levels that ranged from 20 to 80 mmHg. The data obtained from 41 E neurons were used to derive an empirical model that quantifies the average relationship for F n versus both Pt and PaCO2 . This model can be used to predict the time course and magnitude of E neuronal responses to these inputs. These data suggest that the interaction between PaCO2 and PSR-mediated excitation and inhibition of F n is mainly additive, but synergism between PaCO2 and excitatory inputs is also present. The implications of these findings are discussed.

Modulation of upper airway muscle activities by bronchopulmonary afferents

2006 ◽  
Vol 101 (2) ◽  
pp. 609-617 ◽  
Author(s):  
E. Fiona Bailey ◽  
Ralph F. Fregosi
Keyword(s):  
Airway Obstruction ◽  
Upper Airway ◽  
Review Of The Literature ◽  
Lung Inflation ◽  
Hyoid Arch ◽  
Lack Of Information ◽  
Stretch Receptors ◽  
C Fiber ◽  
Pulmonary Stretch Receptors ◽  
Upper Airway Muscles

Here we review the influence of bronchopulmonary receptors (slowly and rapidly adapting pulmonary stretch receptors, and pulmonary/bronchial C-fiber receptors) on respiratory-related motor output to upper airway muscles acting on the larynx, tongue, and hyoid arch. Review of the literature shows that all muscles in all three regions are profoundly inhibited by lung inflation, which excites slowly adapting pulmonary stretch receptors. This widespread coactivation includes the recruitment of muscles that have opposing mechanical actions, suggesting that the stiffness of upper airway muscles is highly regulated. A profound lack of information on the modulation of upper airway muscles by rapidly adapting receptors and bronchopulmonary C-fiber receptors prohibits formulation of a conclusive opinion as to their actions and underscores an urgent need for new studies in this area. The preponderance of the data support the view that discharge arising in slowly adapting pulmonary stretch receptors plays an important role in the initiation of the widespread and highly coordinated recruitment of laryngeal, tongue, and hyoid muscles during airway obstruction.

Characteristics of sustained graded inspiratory inhibition by phasic lung volume changes

1980 ◽  
Vol 48 (2) ◽  
pp. 302-307 ◽  
Author(s):  
J. P. Baker ◽  
J. E. Remmers
Keyword(s):  
Lung Volume ◽  
Dynamic Properties ◽  
Constant Flow ◽  
Afferent Activity ◽  
Volume Changes ◽  
Lung Inflation ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Integrative Processing ◽  
Inhibitory Threshold

The dynamic characteristics of graded reversible inspiratory inhibition by vagal feedback were investigated in pentobarbital-anesthetized paralyzed cats, ventilated with a servo respirator. The volume and time associated with various levels of graded inhibition were determined by using a series of constant-flow lung inflations. Protracted phrenic inhibition was produced by lung inflation, which was arrested when the phrenic discharge was partially inhibited. Thereafter, the volume was withdrawn along a trajectory that approximately paralleled the fall in inhibitory threshold. This volume-withdrawal trajectory would be expected to produce a sustained nearly constant level of inhibition based on the results determined from the constant-flow inflations. However, the observed inhibition exceeded that expected, increasing to a maximum and then decreasing to expected values over a period ranging from 1 to 2 s in most animals. This excess inhibition cannot be attributed to the known dynamic properties of pulmonary stretch receptors; their activity should be reduced, for any particular lung volume, during the volume withdrawal maneuver. These results suggest a central integrative processing of vagal afferent activity that causes inhibition to lag volume. This delay acts to promote inspiratory off-switching because it prevents the development of a protracted period of reversible inhibition.

Influence of CPAP on reflex responses to tracheal irritation in anesthetized humans

1989 ◽  
Vol 67 (3) ◽  
pp. 954-958 ◽  
Author(s):  
T. Nishino ◽  
K. Sugimori ◽  
K. Hiraga ◽  
Y. Hond
Keyword(s):  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Lung Inflation ◽  
Cough Reflex ◽  
Reflex Responses ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Spontaneously Breathing ◽  
Different Levels ◽  
Reflex Cough

We investigated the effects of lung inflation during continuous positive airway pressure breathing (CPAP) on airway defensive reflexes in 10 enflurane-anesthetized spontaneously breathing humans. The airway defensive reflexes were induced by instillation into the trachea of 0.5 ml of distilled water at two different levels of end-expiratory pressure (0 and 10 cmH2O CPAP). The tracheal irritation at an end-expiratory pressure of 0 cmH2O caused a variety of reflex responses including apnea, spasmodic panting, expiration reflex, cough reflex, an increase in heart rate, and an increase in blood pressure. Lung inflation during CPAP of 10 cmH2O did not exert any influence on these reflex responses in terms of the types, latencies, and durations of reflex responses although the intensity of the expiration reflex and cough reflex was augmented by lung inflation. Our results suggest that the pulmonary stretch receptors do not play an important role in the mechanisms of airway defensive reflexes in humans.

Reductions of neural activities to upper airway muscles after elevations in static lung volume

1992 ◽  
Vol 73 (2) ◽  
pp. 701-707 ◽  
Author(s):  
W. M. St John ◽  
D. Zhou
Keyword(s):  
Lung Volume ◽  
Cranial Nerve ◽  
Cranial Nerves ◽  
Upper Airway ◽  
Airway Patency ◽  
Reflex Mechanism ◽  
Lung Inflation ◽  
Tracheal Pressure ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors

We evaluated the hypothesis that the tonic discharge of pulmonary stretch receptors significantly influences the respiratory-modulated activities of cranial nerves. Decerebrate and paralyzed cats were ventilated with a servo-respirator, which produced changes in lung volume in parallel with integrated phrenic activity. Activities of the facial, hypoglossal, and recurrent laryngeal nerves and nerves to the thyroarytenoid muscle and triangularis sterni were recorded. After a stereotyped pattern of lung inflation, tracheal pressure was held at 1, 2, 4, or 6 cmH2O during the subsequent ventilatory cycle. Increases in tracheal pressure caused progressive reductions in both inspiratory and expiratory cranial nerve activities and progressive elevations in triangularis sterni discharge; peak levels of phrenic activity declined modestly. Similar changes were observed in normocapnia and hypercapnia. We conclude that the tonic discharge of pulmonary stretch receptors is an important determinant of the presence and magnitude of respiratory-modulated cranial nerve activity. This reflex mechanism may maintain upper airway patency and also regulate expiratory airflow.

Responses of pulmonary stretch receptors during ramp inflations of the lung

1986 ◽  
Vol 61 (1) ◽  
pp. 344-352 ◽  
Author(s):  
A. I. Pack ◽  
M. D. Ogilvie ◽  
R. O. Davies ◽  
R. J. Galante
Keyword(s):  
Transpulmonary Pressure ◽  
Type I ◽  
Single Population ◽  
Lung Inflation ◽  
Lung Expansion ◽  
Constant Rate ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Multiple Levels ◽  
Pulmonary Stretch Receptor

Studies were conducted in anesthetized paralyzed dogs to determine how the dynamic and proportional sensitivity of pulmonary stretch receptors change during lung inflation. The firing of each receptor was examined at multiple levels of static transpulmonary pressure and during multiple identical inflations at each of several rates. The averaged response of the receptor was computed and receptor activity related to transpulmonary pressure. On the basis of a quantitative criterion, employed to distinguish type I from type II receptors, the receptors could not be divided into distinct subpopulations. Thus all receptors were treated as coming from a single population. For all receptors we observed that their proportional sensitivity (increases in firing produced by increases in lung expansion at a constant rate of inflation) declined as the lung was inflated. In contrast, the dynamic sensitivity (increases in firing produced by increased rates of inflation at constant transpulmonary pressure) increased or remained relatively constant with increasing lung expansion. Thus, as inflation volume increases, the pulmonary stretch receptor acts increasingly as a rate receptor. The rate of inflation may have a more important role in control of the inspiratory duration than previously realized.

Hering–Breuer inflation reflex in young and adult mammals

1981 ◽  
Vol 59 (9) ◽  
pp. 1017-1021 ◽  
Author(s):  
C. Gaultier ◽  
J. P. Mortola
Keyword(s):  
Mechanical Properties ◽  
Respiratory System ◽  
Lung Volume ◽  
Young Animal ◽  
Transpulmonary Pressure ◽  
Lung Inflation ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Chemical Stimuli ◽  
Underlying Mechanisms

The apnea following lung inflation (Hering–Breuer expiratory promoting reflex) is a vagally mediated reflex which is initiated by the activation of pulmonary stretch receptors (PSR) and terminated by the interaction of several factors, which include adaptation of PSR, chemical stimuli, level of anaesthesia, and body temperature. Since PSR activity is determined by the changes in airway tension, the interpretation of the strength of vagal reflexes on the basis of changes in lung volume rather than transpulmonary pressure can be misleading when the mechanical properties of the respiratory system are not constant. In this study we compared the reflex apnea resulting from lung inflation of young and adult mammals, the respiratory system of which have very different mechanical properties. If the response is compared on the basis of similar changes in lung volume, it can be considered weaker or stronger in the young depending upon the normalizing parameter used. However, when considered on the basis of the relative changes in transpulmonary pressure, which better reflects the activation of PSR, the reflex is weaker in young rats and rabbits than in their adult counterparts and similar in dogs. The analysis of the underlying mechanisms suggests a weaker vagal contribution in the young animal, but a satisfactory conclusion requires a better knowledge of the factors which, in the younger animals, result in the termination of the apnea.

Investigation of Changes in Membrane Potential and Rhythmic Activity of the Retzius Neuron upon Stimulation of the Sensory P-Neuron

2020 ◽  
pp. 137-144
Author(s):  
T.A. Kazakova ◽  
A.I. Yusipovich ◽  
G.V. Maksimov
Keyword(s):  
Electrical Stimulation ◽  
Membrane Potential ◽  
Sensory Neurons ◽  
Rhythmic Activity ◽  
Nerve Fibers ◽  
Retzius Neuron ◽  
Retzius Cell ◽  
Retzius Cells ◽  
P Cells ◽  
Stimulation Of

It was found that in "natural neural networks", ganglia of the nervous system of a leech, the frequency of rhythmic excitation (a series of nerve impulses, RE) of one neuron is modulated upon activation of other neurons. Changes in the electrophysiological characteristics of the leech Retzius cell in response to electrical stimulation of one of the sensory neurons (P-cells) were revealed. Registration of changes in the membrane potential of neurons, as well as electrical stimulation of the P-cell was carried out using microelectrodes introduced into the cells. It was found that during electrical stimulation, P-cells increase the frequency of spontaneous RE of Retzius cells, the membrane potential of P-cells increases, but Retzius cells do not change. With an increase in the duration of stimulation, the RE frequency increases in both the P-cell and the Retzius cell. It has been found that RE Retzius cells, upon stimulation of P-cells, arise against the background of RE of the Retzius cell. Thus, during RE of sensory neurons and synaptic transmission to the Retzius cell, RE frequency modulation occurs. According to the authors, changes in the frequency of spontaneous RE of the Retzius neuron in the "natural neural network" are associated not only with a change in the RE frequency during excitation along nerve fibers from skin receptors, but also with the transformation of RE both between cells of one ganglion and between cells in different ganglia leech nerve chain

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