scholarly journals Intercostal muscle motor behavior during tracheal occlusion conditioning in conscious rats

2016 ◽  
Vol 120 (7) ◽  
pp. 792-800 ◽  
Author(s):  
Poonam B. Jaiswal ◽  
Paul W. Davenport
Keyword(s):  
Respiratory Activity ◽  
Motor Behavior ◽  
Respiratory Muscles ◽  
Experimental Period ◽  
Emg Activity ◽  
Intercostal Muscle ◽  
Load Compensation ◽  
Conscious Rats ◽  
Loaded Breathing ◽  
Conscious Animals

A respiratory load compensation response is characterized by increases in activation of primary respiratory muscles and/or recruitment of accessory respiratory muscles. The contribution of the external intercostal (EI) muscles, which are a primary respiratory muscle group, during normal and loaded breathing remains poorly understood in conscious animals. Consciousness has a significant role on modulation of respiratory activity, as it is required for the integration of behavioral respiratory responses and voluntary control of breathing. Studies of respiratory load compensation have been predominantly focused in anesthetized animals, which make their comparison to conscious load compensation responses challenging. Using our established model of intrinsic transient tracheal occlusions (ITTO), our aim was to evaluate the motor behavior of EI muscles during normal and loaded breathing in conscious rats. We hypothesized that 1) conscious rats exposed to ITTO will recruit the EI muscles with an increased electromyogram (EMG) activation and 2) repeated ITTO for 10 days would potentiate the baseline EMG activity of this muscle in conscious rats. Our results demonstrate that conscious rats exposed to ITTO respond by recruiting the EI muscle with a significantly increased EMG activation. This response to occlusion remained consistent over the 10-day experimental period with little or no effect of repeated ITTO exposure on the baseline ∫EI EMG amplitude activity. The pattern of activation of the EI muscle in response to an ITTO is discussed in detail. The results from the present study demonstrate the importance of EI muscles during unloaded breathing and respiratory load compensation in conscious rats.

Ventilatory failure during loaded breathing: the role of central neural drive

1988 ◽  
Vol 65 (1) ◽  
pp. 249-255 ◽  
Author(s):  
J. F. Watchko ◽  
T. A. Standaert ◽  
D. E. Mayock ◽  
G. Twiggs ◽  
D. E. Woodrum
Keyword(s):  
Minute Ventilation ◽  
Respiratory Muscles ◽  
Muscle Performance ◽  
Emg Activity ◽  
Base Line ◽  
Force Frequency ◽  
Peripheral Muscle ◽  
Arterial Blood ◽  
Loaded Breathing ◽  
Ventilatory Failure

Minute ventilation (VE), arterial blood gases, diaphragmatic electromyogram (EMG) activity, centroid frequency (Fc) and peak inspiratory airway pressures (Paw) were measured in five unanesthetized tracheostomized infant monkeys during various intensities of inspiratory resistive loaded breathing (IRL) until either 1) ventilatory failure occurred (failed trial) or 2) normocapnia was sustained for 1 h (successful trial). During successful trials VE and arterial PCO2 (PaCO2) were sustained at base-line levels, and an increase in peak integrated diaphragmatic EMG activity and peak inspiratory Paw occurred. In contrast, during ventilatory failure runs, VE decreased and PaCO2 rose compared with their respective base-line values. The fall in VE occurred secondary to a significant decline in breathing frequency. Tidal volume was sustained at base-line levels during all trials (both successful and failed groups). Inspiratory Paw's and peak moving time average EMG were sustained at elevated levels during ventilatory failure runs, suggesting that the respiratory muscles did not fail as pressure generators. Furthermore, the EMG Fc did not change from base line during either successful or failed trials. These data suggest that peripheral muscle fatigue did not occur, although in the absence of a more direct test of muscle performance, i.e., a force-frequency curve, we cannot rule out the possibility that a component of peripheral failure contributed to our results. Ventilatory failure during severe IRL in the infant monkey was most clearly associated with an alteration in the respiratory center timing mechanism, i.e., such failure was a function of a decline in respiratory frequency.

Electromyographic response of respiratory muscles during elastic loading

1976 ◽  
Vol 230 (3) ◽  
pp. 675-683 ◽  
Author(s):  
SG Kelsen ◽  
MD Altose ◽  
NN Stanley ◽  
RS Levinson ◽  
NS Cherniack ◽  
...  
Keyword(s):  
Motor Neuron ◽  
Motor Neurons ◽  
Respiratory Muscles ◽  
Reflex Activity ◽  
Emg Activity ◽  
Intercostal Muscle ◽  
Co2 Rebreathing ◽  
Elastic Loading ◽  
Anesthetized Dogs ◽  
Vagal Cooling

The response of respiratory motor neurons to graded elastic loading was assessed in anesthetized dogs by recording the electromyogram (EMG) from the diaphragm (ED) and the intercostal muscle (EIC). Elastic loads were applied for 1-20 breaths. The effects of changes in PCO2 on respiratory motor neuron output was assessed by applying loads during the course of CO2 rebreathing. On the first loaded breath, ED and EIC increased reflexly due chiefly to prolongation of inspiration. Vagotomy or vagal cooling to block the Hering-Breuer reflex eliminated the increase in ED and diminished the increase in EIC. During the second to fifth breath, the level of EMG activity was disproportionately high for the level of PCO2, suggesting an additional reflex component over and above the reflex activity present on the first loaded breath.

scholarly journals Effect of expiratory loaded breathing during moderate exercise on intercostal muscle oxygenation

2020 ◽  
Vol 15 ◽  
Author(s):  
Quentin Bretonneau ◽  
Aurélien Pichon ◽  
Claire De Bisschop
Keyword(s):  
Near Infrared ◽  
Saturation Index ◽  
Respiratory Muscles ◽  
Muscle Oxygenation ◽  
Dynamic Hyperinflation ◽  
Moderate Exercise ◽  
Intercostal Muscle ◽  
Loaded Breathing ◽  
Concentration Changes ◽  
High Level

Background: In patients with obstructive lung disease, maintaining adequate ventilation during exercise may require greater contraction of the respiratory muscles, which may lead to a compression of muscle capillaries. Furthermore, dynamic hyperinflation (DH) is frequent during exercise in these patients, as it allows to reach higher expiratory flows and to satisfy respiratory demand. However, in such situation, intercostal muscles are likely to be stretched, which could affect the diameter of their capillaries. Thus, in a context of high level of expiratory resistance, intercostal muscle oxygenation may be disturbed during exercise, especially if DH occurs.Methods: Twelve participants (22±2 years) performed two sessions of moderate exercise (20 min) by breathing freely with and without a 20-cmH2O expiratory threshold load (ETL). Tissue saturation index (TSI) and concentration changes from rest (∆) in oxygenated ([O2Hb]) and total haemoglobin ([tHb]) were measured in the seventh intercostal space using near-infrared spectroscopy. Respiratory, metabolic and cardiac variables were likewise recorded.Results: Throughout exercise, dyspnea was higher and TSI was lower in ETL condition than in control (p<0.01). After a few minutes of exercise, ∆ [O2Hb] was also lower in ETL condition, as well as ∆ [tHb], when inspiratory capacity started to be reduced (p<0.05). Changes in [O2Hb] and dyspnea were correlated with changes in expiratory flow rate (Vt/Te) (r = -0.66 and 0.66. respectively; p<0.05).Conclusion: During exercise with ETL, impaired muscle oxygenation could be due to a limited increase in blood volume resulting from strong muscle contraction and/or occurrence of DH.

Patterns of neural and muscular electrical activity in costal and crural portions of the diaphragm

1989 ◽  
Vol 66 (5) ◽  
pp. 2092-2100 ◽  
Author(s):  
L. M. Oyer ◽  
S. L. Knuth ◽  
D. K. Ward ◽  
D. Bartlett
Keyword(s):  
Electrical Activity ◽  
Phrenic Nerve ◽  
Respiratory Activity ◽  
Respiratory Muscles ◽  
Emg Activity ◽  
Neural Responses ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Central Respiratory Activity ◽  
Spontaneously Breathing

To determine whether the central respiratory drives to costal and crural portions of the diaphragm differ from each other in response to chemical and mechanical feedbacks, activities of costal and crural branches of the phrenic nerve were recorded in decerebrate paralyzed cats, studied either with vagi intact and servo-ventilated in accordance with their phrenic nerve activity or vagotomized and ventilated conventionally. Costal and crural electromyograms (EMGs) were recorded in decerebrate spontaneously breathing cats. Hypercapnia and hypoxia resulted in significant increases in peak integrated costal, crural, and whole phrenic nerve activities when the vagi were either intact or cut. However, there were no consistent differences between costal and crural neural responses. Left crural EMG activity was increased significantly more than left costal EMG activity in response to hypercapnia and hypoxia. These results indicate that the central neural inputs to costal and crural portions of the diaphragm are similar in eupnea and in response to chemical and mechanical feedback in decerebrate paralyzed cats. The observed differences in EMG activities in spontaneously breathing animals must arise from modulation of central respiratory activity by mechanoreceptor feedback from respiratory muscles, likely the diaphragm itself.

N-acetylcysteine administration alters the response to inspiratory loading in oxygen-supplemented rats

1997 ◽  
Vol 82 (4) ◽  
pp. 1119-1125 ◽  
Author(s):  
G. S. Supinski ◽  
D. Stofan ◽  
R. Ciufo ◽  
A. Dimarco
Keyword(s):  
Free Radical ◽  
Respiratory Failure ◽  
Respiratory Muscles ◽  
Treated Group ◽  
Respiratory Arrest ◽  
Saline Group ◽  
Free Radical Scavenger ◽  
Radical Scavenger ◽  
Resistive Load ◽  
Loaded Breathing

Supinski, G. S., D. Stofan, R. Ciufo, and A. DiMarco. N-acetylcysteine administration alters the response to inspiratory loading in oxygen-supplemented rats. J. Appl. Physiol. 82(4): 1119–1125, 1997.—Based on recent studies, it has been suggested that free radicals are elaborated in the respiratory muscles during strenuous contractions and contribute to the development of muscle fatigue. If this theory is correct, then it should be possible to attenuate the development of diaphragm fatigue and/or delay the onset of respiratory failure during loaded breathing by administering a free radical scavenger. The purpose of the present experiment was, therefore, to examine the effect of N-acetylcysteine (NAC), a free radical scavenger and glutathione precursor, on the evolution of respiratory failure in decerebrate unanesthetized rats breathing against a large inspiratory resistive load. We compared the inspiratory volume and pressure generation over time in animals pretreated with either saline or NAC (150 mg/kg) and then loaded until respiratory arrest. After arrest, the diaphragm was excised, and samples were assayed for reduced (GSH) and oxidized glutathione. As a control, we also assessed respiratory function and glutathione concentrations in groups of nonloaded saline- and NAC-treated animals. We found that NAC-treated animals were able to tolerate loading better than the saline-treated group, maintaining higher inspiratory pressures and sustaining higher inspired volumes. Administration of NAC also increased the time that animals could tolerate loading before the development of respiratory arrest. In addition, although saline-treated loaded animals had significant reductions in diaphragmatic GSH levels compared with unloaded controls, the magnitude of this reduction was blunted by NAC administration (i.e., GSH averaged 965 ± 113, 568 ± 83, 907 ± 39, and 784 ± 61 nmol/g for unloaded-saline, loaded-saline, unloaded-NAC, and loaded-NAC groups, P< 0.05, with the value for the loaded-saline group lower than the values for the two unloaded groups; GSH for the loaded-NAC group was not different, however, from unloaded controls). These data demonstrate that administration of NAC, a free radical scavenger, slows the rate of development of respiratory failure during inspiratory resistive loading.

Role of Primate Magnocellular Red Nucleus Neurons in Controlling Hand Preshaping During Reaching to Grasp

2001 ◽  
Vol 85 (4) ◽  
pp. 1461-1478 ◽  
Author(s):  
Peter L. E. Van Kan ◽  
Martha L. McCurdy
Keyword(s):  
Task Performance ◽  
Motor Behavior ◽  
Red Nucleus ◽  
Reaching Movements ◽  
Emg Activity ◽  
Reach To Grasp ◽  
Spinal Circuitry ◽  
A Minor ◽  
Hand Preshaping

Reaching to grasp is of fundamental importance to primate motor behavior and requires coordinating hand preshaping with limb transport and grasping. We aimed to clarify the role of cerebellar output via the magnocellular red nucleus (RNm) to the control of reaching to grasp. Rubrospinal fibers originating from RNm constitute one pathway by which cerebellar output influences spinal circuitry directly. We recorded discharge from individual forelimb RNm neurons while monkeys performed a reach-to-grasp task and two tasks that were similar to the reach-to-grasp task in trajectory, amplitude, and direction but did not include a grasp. One of these, the device task, elicited reaches while holding a handle, and the other, the free-reach task, elicited reaches that did not require any specific hand use for task performance. The results demonstrate that coordinated whole-limb reaching movements are associated with large discharge modulations of RNm neurons predominantly when hand use is included. Therefore RNm neurons can at best only make a minor contribution to the control of reaching movements that lack hand use. We evaluated relations between the discharge of individual RNm neurons and electromyographic (EMG) activity of forelimb muscles during the reach-to-grasp task by comparing times of peak RNm discharge to times of peak EMG activity. The results are consistent with the view that RNm discharge may contribute to EMG activity of both distal and proximal muscles during reaching to grasp especially digit extensor and limb elevation muscles. Relations between the discharge of individual RNm neurons and movements of the metacarpi-phalangeal (MCP), wrist, elbow, and shoulder joints during individual trials of task performance were quantified by parametric correlation analyses on a subset of neurons studied during the reach-to-grasp and free-reach tasks. The results indicate that MCP extensions were consistently preceded by bursts of RNm discharge, and strong correlations were observed between parameters of discharge and the duration, velocity, and amplitude of corresponding MCP extensions. In contrast, relations between discharge and movements of proximal joints were poorly represented, and RNm discharge was not related to the speed of limb transport. Based on our data and those of others, we hypothesize that cerebellar output via RNm is specialized for controlling hand use and conclude that RNm may contribute to the control of hand preshaping during reaching to grasp by activating muscle synergies that produce the appropriate MCP extension at the appropriate phase of limb transport.

Effect of inspiratory muscle unloading on arousal responses to CO2 and hypoxia in sleeping dogs

1993 ◽  
Vol 74 (3) ◽  
pp. 1325-1336 ◽  
Author(s):  
R. J. Kimoff ◽  
L. F. Kozar ◽  
F. Yasuma ◽  
T. D. Bradley ◽  
E. A. Phillipson
Keyword(s):  
Rem Sleep ◽  
Respiratory Muscles ◽  
Nrem Sleep ◽  
Inspiratory Muscle ◽  
Transversus Abdominis ◽  
Emg Activity ◽  
Arousal Threshold ◽  
Inspiratory Muscles ◽  
Arousal Response ◽  
Muscle Unloading

Chemical respiratory stimuli can induce arousal from sleep, but the specific mechanisms involved have not been established. Therefore, we tested the hypothesis that mechanoreceptor stimuli arising in the ventilatory apparatus have a role in the arousal responses to progressive hypercapnia and hypoxia by comparing arousal responses during spontaneous ventilation with those obtained when the inspiratory muscles were unloaded by mechanical ventilatory assistance. Studies were performed in three trained dogs in which the adequacy of inspiratory muscle unloading was verified by diaphragmatic electromyographic (EMG) recordings. In rapid-eye-movement (REM) sleep the arousal threshold during progressive hypercapnia increased from 68.4 +/- 0.5 (SE) mmHg during spontaneous runs to 72.3 +/- 0.8 mmHg during mechanically assisted runs (P < 0.01). In contrast there were no changes in arousal responses to hypercapnia during non-REM (NREM) sleep or to hypoxia in either NREM or REM sleep. However, during the assisted hypoxic runs, EMG activity of the transversus abdominis muscle was increased compared with the unassisted runs; therefore, the effects on arousal threshold of unloading the inspiratory muscles may have been offset by increased loading of the expiratory muscles. The findings indicate that even in the absence of added mechanical loads, mechanoreceptor stimuli probably arising in the respiratory muscles contribute to the arousal response to hypercapnia during REM sleep.

scholarly journals A simple method for oral administration of drugs in solid form to fully conscious rats

1983 ◽  
Vol 17 (1) ◽  
pp. 50-54 ◽  
Author(s):  
E. R. Lax ◽  
K. Militzer ◽  
A. Trauschel
Keyword(s):  
Oral Administration ◽  
Tissue Damage ◽  
Training Period ◽  
Solid Materials ◽  
Simple Method ◽  
Conscious Rats ◽  
Solid Form ◽  
Conscious Animals ◽  
Peristaltic Action ◽  
Design And Application

The design and application of a simple capsule administration tube for miniature capsules are described. Experiments with rats have shown that the tube is capable of depositing capsules at the distal end of the oesophagus. Regardless of the location of the capsule in the oesophagus, provided normal peristaltic action occurs, the capsule will have reached the stomach and discharged its contents within 10 min. After a short training period of 3-4 days the insertion of the tube does not appear to cause the rats undue discomfort, nor does it cause tissue damage. The procedure, which can be performed rapidly by 1 technician, is ideally suited for dispensing solid materials to fully conscious animals.

scholarly journals Recruitment and plasticity in diaphragm, intercostal, and abdominal muscles in unanesthetized rats

2014 ◽  
Vol 117 (2) ◽  
pp. 180-188 ◽  
Author(s):  
A. Navarrete-Opazo ◽  
G. S. Mitchell
Keyword(s):  
Respiratory Muscles ◽  
Abdominal Muscle ◽  
Emg Activity ◽  
Abdominal Muscles ◽  
Emg Amplitude ◽  
Inspiratory Activity ◽  
Unanesthetized Animals ◽  
Long Term Facilitation ◽  
Relative Capacity

Although rats are a frequent model for studies of plasticity in respiratory motor control, the relative capacity of rat accessory respiratory muscles to express plasticity is not well known, particularly in unanesthetized animals. Here, we characterized external intercostal (T2, T4, T5, T6, T7, T8, T9 EIC) and abdominal muscle (external oblique and rectus abdominis) electromyogram (EMG) activity in unanesthetized rats via radiotelemetry during normoxia (Nx: 21% O2) and following acute intermittent hypoxia (AIH: 10 × 5-min, 10.5% O2; 5-min intervals). Diaphragm and T2–T5 EIC EMG activity, and ventilation were also assessed during maximal chemoreceptor stimulation (MCS: 7% CO2, 10.5% O2) and sustained hypoxia (SH: 10.5% O2). In Nx, T2 EIC exhibits prominent inspiratory activity, whereas T4, T5, T6, and T7 EIC inspiratory activity decreases in a caudal direction. T8 and T9 EIC and abdominal muscles show only tonic or sporadic activity, without consistent respiratory activity. MCS increases diaphragm and T2 EIC EMG amplitude and tidal volume more than SH (0.94 ± 0.10 vs. 0.68 ± 0.05 ml/100 g; P < 0.001). Following AIH, T2 EIC EMG amplitude remained above baseline for more than 60 min post-AIH (i.e., EIC long-term facilitation, LTF), and was greater than diaphragm LTF (41.5 ± 1.3% vs. 19.1 ± 2.0% baseline; P < 0.001). We conclude that 1) diaphragm and rostral T2–T5 EIC muscles exhibit inspiratory activity during Nx; 2) MCS elicits greater ventilatory, diaphragm, and rostral T2–T5 EIC muscle activity vs. SH; and 3) AIH induces greater rostral EIC LTF than diaphragm LTF.

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