Cerebellar role in the load-compensating response of expiratory muscle

1994 ◽  
Vol 77 (3) ◽  
pp. 1232-1238 ◽  
Author(s):  
F. Xu ◽  
D. T. Frazier
Keyword(s):  
Spinal Column ◽  
Transversus Abdominis ◽  
Vagal Afferents ◽  
Electromyographic Activity ◽  
Tracheal Occlusion ◽  
Expiratory Muscle ◽  
Expiratory Muscles ◽  
Lung Airways ◽  
Dorsal Spinal

The hypothesis that the cerebellum is involved in the load-compensating response of expiratory muscles to expiratory tracheal occlusion was tested in anesthetized cats. A continuous expiratory threshold load (ETL; 5 cmH2O) was applied to elicit consistent phasic baseline electromyographic activity in the transversus abdominis muscle (EMGab). Tracheal occlusion for single expirations (TOE) were applied, and the evoked responses were compared in the intact and decerebellate preparation. Cold blockade of the dorsal spinal column (C5-7) and bilateral vagal inactivation (cold blockade or transection) were employed to determine the role of afferents from the lung, airways, chest wall, and diaphragm in shaping the cerebellar involvement in the motor response. The results showed that 1) decerebellation increased the baseline amplitude of the integrated EMGab (fEMGab) activity (P < 0.05) with little change in expiratory duration, 2) TOE applied after decerebellation markedly increased the expiratory duration compared with the intact values (P < 0.05), with little effect on the peak fEMGab, 3) cooling the dorsal spinal columns (C5-7) did not significantly affect EMGab responses in the intact or decerebellate preparations, and 4) vagal inactivation in the intact or decerebellate preparation significantly eliminated the fEMGab responses to ETL and TOE. We conclude that the cerebellum is involved in the modulation of transversus abdominis activity during ETL and TOE. Vagal afferents provide the major sensory input for the cerebellar modulation of the expiratory loading response.

Mechanical role of expiratory muscle recruitment during eupnea in supine anesthetized dogs

1991 ◽  
Vol 70 (5) ◽  
pp. 2025-2031 ◽  
Author(s):  
M. A. Schroeder ◽  
H. Y. Tao ◽  
G. A. Farkas
Keyword(s):  
Tidal Volume ◽  
Spontaneous Breathing ◽  
Transversus Abdominis ◽  
Substantial Contribution ◽  
Emg Activity ◽  
Expiratory Muscle ◽  
Anesthetized Dogs ◽  
Expiratory Muscles ◽  
Phasic Activation

To assess the mechanical role of the expiratory musculature during eupnea, we recorded the electromyographic (EMG) activity of the triangularis sterni, the external oblique, and the transversus abdominis in eight supine lightly anesthetized dogs and have measured the volume generated by the phasic activation of the expiratory muscles. Activation of the expiratory muscles was invariably associated with a decrease in lung volume below the relaxed position of the respiratory system, a volume equal to 41.3 +/- 8.4 ml. This volume represented roughly 20% of tidal volume generated during spontaneous breathing. The fractional expiratory contribution to the tidal volume was unrelated to the size of the animal. Traction on the forelimbs (limb extension), however, tended to enhance the phasic expiratory activation of both the triangularis sterni and the transversus abdominis in the majority of animals. Moreover, after limb extension, the fractional contribution of tidal volume attributed to the phasic activation of the expiratory muscles increased in all but one animal. During spontaneous breathing with the forelimbs extended, roughly 25% of tidal volume was found to be due directly to phasic expiratory muscle contraction. The present observations firmly establish that in supine lightly anesthetized dogs breathing at rest the expiratory component of tidal volume represents a substantial contribution.

Regulation of expiratory muscles during postnatal development in anesthetized piglets

1993 ◽  
Vol 74 (6) ◽  
pp. 2655-2660 ◽  
Author(s):  
I. Litmanovitz ◽  
R. J. Martin ◽  
M. A. Haxhiu ◽  
L. Cattarossi ◽  
B. Haxhiu-Poskurica ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Age Groups ◽  
Respiratory Control ◽  
Transversus Abdominis ◽  
Vagal Afferents ◽  
Postnatal Life ◽  
Experimental Conditions ◽  
Rib Cage ◽  
Before And After ◽  
Expiratory Muscles

We compared maturation of the responses of the rib cage [triangularis sterni (TS)] and abdominal [transversus abdominis (TA)] expiratory muscles with each other and with the responses of the diaphragm (DIA) during hypercarbic and hypoxic stimulation. Studies were performed in anesthetized (urethan and chloralose) piglets of two age groups (< 6 days, n = 10; 14–21 days, n = 11) before and after bilateral cervical vagotomy. Hypercarbia (7% CO2–93% O2) was associated with comparable sustained increases in the minute electromyograms (EMGs) of both TS and TA, which were closely coupled to the DIA responses in both age groups. Hypoxia (12% O2–88% N2) caused a biphasic response of the minute EMG of both expiratory muscles and DIA; these biphasic responses were less prominent at 14-21 days than at < 6 days. Vagotomy caused an increase in the amplitude of both TS and TA (38 +/- 30 and 27 +/- 21%, respectively) as well as the DIA (45 +/- 16%) but did not affect their relative responses to chemostimulation. We conclude that during postnatal development 1) the rib cage and abdominal expiratory muscle responses to chemostimulation are coupled to each other and parallel those of the DIA and 2) the presence of vagal afferents attenuates the drive to both inspiratory and expiratory motoneurons under the current experimental conditions but does not influence the relative responses of expiratory muscles and DIA to hypercarbia or hypoxia. We speculate that comparable activation of inspiratory and expiratory pumping muscles serves to stabilize respiratory control in the face of altered chemosensory or vagal inputs during early postnatal life.

Electrical activation of expiratory muscles increases with time in pentobarbital-anesthetized dogs

1992 ◽  
Vol 72 (6) ◽  
pp. 2285-2291 ◽  
Author(s):  
D. O. Warner ◽  
M. J. Joyner ◽  
K. Rehder
Keyword(s):  
Electrical Activity ◽  
Important Variable ◽  
Transversus Abdominis ◽  
Implanted Electrodes ◽  
Expiratory Muscle ◽  
Inspiratory Muscles ◽  
Anesthetized Dogs ◽  
Expiratory Muscles ◽  
Muscle Groups ◽  
Over Time

Although the pentobarbital-anesthetized dog is often used as a model in studies of respiratory muscle activity during spontaneous breathing, there is no information regarding the stability of the pattern of breathing of this model over time. The electromyograms of several inspiratory and expiratory muscle groups were measured in six dogs over a 4-h period by use of chronically implanted electrodes. Anesthesia was induced with pentobarbital sodium (25 mg/kg iv), with supplemental doses to maintain constant plasma pentobarbital concentrations. Phasic electrical activity increased over time in the triangularis sterni, transversus abdominis, and external oblique muscles (expiratory muscles). The electrical activity of the costal diaphragm, crural diaphragm, and parasternal intercostal muscles (inspiratory muscles) was unchanged. These changes in electrical activity occurred despite stable plasma levels of pentobarbital and arterial PCO2. They were associated with changes in chest wall motion and an increased tidal volume with unchanged breathing frequency. We conclude that expiratory muscle groups are selectively activated with time in pentobarbital-anesthetized dogs lying supine. Therefore the duration of anesthesia is an important variable in studies using this model.

Role of vagal and spinal sensory pathways on eupneic diaphragmatic activity

1986 ◽  
Vol 60 (2) ◽  
pp. 479-485 ◽  
Author(s):  
Y. Jammes ◽  
M. J. Mathiot ◽  
S. Delpierre ◽  
C. Grimaud
Keyword(s):  
Spinal Reflexes ◽  
Vagal Afferents ◽  
Tracheal Occlusion ◽  
Sensory Pathways ◽  
Cervical Vagotomy ◽  
Experimental Protocols ◽  
Spinal Section ◽  
Spinal Afferents ◽  
Alpha Chloralose

The interactions between vagal and spinal afferents in the control of eupneic diaphragmatic activity were studied in two groups of cats anesthetized either with pentobarbital sodium (SPB) or with ethyl carbamate-alpha-chloralose (ECC), which enhanced spinal reflexes. Under both conditions of anesthesia two experimental protocols were performed: 1) bilateral cervical vagotomy followed by spinal section at C8 level or 2) spinal section followed by vagotomy. Changes in integrated diaphragmatic activity (Edi) were studied during eupneic ventilation and tracheal occlusion at end expiration. Vagotomy always significantly increased the amplitude of Edi during eupnea (SPB + 30%; ECC + 15%) and prolonged its duration (Tdi) (SPB + 110%; ECC + 75%) but did not modify the overall shape of the Edi vs. time relationship. Spinal section induced reverse changes in the amplitude of Edi, whether vagal afferents were present or suppressed and modified the shape of the Edi wave, but did not significantly modify Tdi. These results indicate that both vagal and spinal afferents may participate in the control of eupneic inspiration but exert different and interdependent influences on the recruitment and firing time of phrenic motoneurons. In addition, Tdi measured during tracheal occlusion (Todi) was markedly prolonged under ECC anesthesia. In this situation spinal section reduced Todi, which became close to the values obtained in intact or spinal cats under SPB anesthesia. Thus the response to tracheal occlusion at end expiration cannot be interpreted as resulting from the sole suppression of volume related vagal information.

Differential respiratory activity of four abdominal muscles in humans

1996 ◽  
Vol 80 (4) ◽  
pp. 1379-1389 ◽  
Author(s):  
T. Abe ◽  
N. Kusuhara ◽  
N. Yoshimura ◽  
T. Tomita ◽  
P. A. Easton
Keyword(s):  
Moving Average ◽  
Standing Position ◽  
Transversus Abdominis ◽  
Ultra Sound ◽  
Emg Activity ◽  
Abdominal Muscles ◽  
Expiratory Muscle ◽  
Expiratory Muscles ◽  
Expiratory Flow ◽  
End Tidal

Together the abdominal muscles contribute significantly to ventilation under some conditions, but there is little information regarding individual recruitment and timing of activation of the four abdominal muscles in humans. Fine-wire electrodes were inserted under direct vision guided by high-resolution ultra-sound into the rectus abdominis (Rectus), external oblique (Extern), internal oblique (Intern), and transversus abdominis (Transv) in nine awake healthy subjects. Airflow, end-tidal CO2, and moving-average EMG signals were recorded during 1) supine resting and CO2-stimulated ventilation and 2) resting ventilation in the standing position. During resting supine breathing, Transv showed significant phasic EMG activity during expiration. As posture changed from supine to standing, phasic activity during resting ventilation was greatest in Transv, with lesser activity in Intern and Extern, while Rectus remained inactive. As CO2 began to increase, Transv was activated first, followed by Intern, the Extern, and finally Rectus. With moderate CO2 stimulation, Transv and Intern were more active than was Extern and Rectus remained least active. EMG activities in the expiratory muscles after cessation of expiratory flow (postexpiratory expiratory activity) and in expiratory muscle activity preceding expiratory flow were observed consistently during supine stimulated ventilation and standing resting ventilation. These activities before and after expiratory airflow were prominent with stimulated ventilation during a substantial portion of inspiration, suggesting dual control of inspiratory pump action by both inspiratory and expiratory muscles, which provide acceleration and braking actions, respectively. These results suggest that in awake humans 1) during resting ventilation, expiration is an active process; 2) abdominal muscles are activated differentially; 3) Transv is the most active, Intern and Extern are intermediate, and Rectus is the least active expiratory muscle; and 4) during stimulated ventilation, inspiratory and expiratory muscles contribute dually to inspiratory pump action.

Central action of tachykinins on activity of expiratory pumping muscles

1990 ◽  
Vol 69 (6) ◽  
pp. 1981-1986 ◽  
Author(s):  
M. A. Haxhiu ◽  
N. S. Cherniack ◽  
E. van Lunteren
Keyword(s):  
Substance P ◽  
Muscle Activity ◽  
Transversus Abdominis ◽  
Neurokinin A ◽  
Moderate Increase ◽  
Neurokinin B ◽  
Expiratory Muscle ◽  
Ventral Medullary Surface ◽  
Expiratory Muscles ◽  
Diaphragm Activity

The central effects of tachykinins (substance P, neurokinin A, and neurokinin B) on the distribution of the motor activity to rib cage and abdominal expiratory muscles were studied in anesthetized tracheotomized spontaneously breathing dogs and cats. Intracisternal application of substance P (11 dogs) in doses of 10(-5) to 10(-4) M caused diaphragm electrical activity to change insignificantly from 19.3 +/- 1.9 to 24.8 +/- 3.2 units (P greater than 0.05), produced a moderate increase of triangularis sterni activity from 12.6 +/- 2.2 to 19.2 +/- 2.2 units (P less than 0.05), and stimulated a large increase of transversus abdominis activity from 9.4 +/- 2.7 to 28.5 +/- 2.6 units (P less than 0.01). Comparable effects were seen with similar doses of neurokinin A (8 dogs) and neurokinin B (3 dogs) administered intracisternally. Local application of substance P to the ventral medullary surface (5 dogs and 4 cats) also caused expiratory muscle activity to increase more than diaphragm activity, and in addition transversus abdominis activity increased to a larger extent than triangularis sterni activity. Furthermore, administration of the substance P antagonist [D-Pro2,D-Trp7,9]-SP to the ventral medullary surface decreased respiratory motor output, with expiratory muscles activity being attenuated to a greater extent than diaphragm activity. Application of neurotensin and N-methyl-D-asparate to the ventral surface of the medulla produced responses similar to those observed as a result of central administration of tachykinin peptides. The results suggest that 1) mammalian tachykinins are involved in the regulation of thoracic and abdominal expiratory muscle activity, 2) these muscles manifest substantial differences in their electrical responses to excitatory neuropeptides acting centrally, and 3) inputs from modulatory neurons located in this vicinity of the ventral medullary surface seem to be distributed unevenly to different expiratory premotor and/or motoneurons.

Functional significance of expiratory muscles during spontaneous breathing in anesthetized dogs

1993 ◽  
Vol 74 (1) ◽  
pp. 238-244 ◽  
Author(s):  
G. A. Farkas ◽  
M. A. Schroeder
Keyword(s):  
Tidal Volume ◽  
Spontaneous Breathing ◽  
Transversus Abdominis ◽  
Relative Role ◽  
Significant Length ◽  
Anesthetized Dogs ◽  
Length Changes ◽  
Expiratory Muscles ◽  
Prone Posture

Recent electromyographic studies in awake and anesthetized dogs have demonstrated that spontaneous breathing in prone dogs is associated with an increased activation of the expiratory muscles compared with that recorded in supine dogs. On the basis of these observations, one would infer that the mechanical role and contribution of the expiratory musculature to the act of breathing are enhanced in the prone posture. The changes in length associated with these postural increases in expiratory muscle electrical activity, however, have not been investigated and formed the basis of our investigation. We examined the active and passive changes in length of expiratory muscles during spontaneous breathing in supine and prone anesthetized dogs and assessed the relative role of the expiratory musculature in the generation of tidal volume. The experiments were performed on eight mongrel dogs anesthetized with pentobarbital sodium. In all eight animals, spontaneous breathing in the prone posture was associated with an increased activation (electromyogram) of the triangularis sterni, external oblique, and transversus abdominis muscles compared with that recorded in the supine posture. We quantitated the role of the expiratory muscles in both postures by measuring the volume difference between relaxation volume of the respiratory system and the end-expiratory lung volume. In the supine animal, 93 ml were attributed to the expiratory musculature, whereas in the prone animal, we noted that 186 ml (P < 0.01) were displaced during expiration, representing 43 and 52% (NS) of tidal volume, respectively. During spontaneous breathing in the supine or prone posture, all three expiratory muscles underwent significant length changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypercapnia on inspiratory and expiratory muscle activity during expiration

1985 ◽  
Vol 59 (5) ◽  
pp. 1560-1565 ◽  
Author(s):  
A. Oliven ◽  
E. C. Deal ◽  
S. G. Kelsen ◽  
N. S. Cherniack
Keyword(s):  
Muscle Activity ◽  
Opposite Effect ◽  
Afferent Activity ◽  
Expiratory Muscle ◽  
Inspiratory Muscles ◽  
Before And After ◽  
Expiratory Muscles ◽  
External Oblique ◽  
Lung Deflation

Persistence of inspiratory muscle activity during the early phase of expiratory airflow slows the rate of lung deflation, whereas heightened expiratory muscle activity produces the opposite effect. To examine the influence of increased chemoreceptor drive and the role of vagal afferent activity on these processes, the effects of progressive hypercapnia were evaluated in 12 anesthetized tracheotomized dogs before and after vagotomy. Postinspiratory activity of inspiratory muscles (PIIA) and the activity of expiratory muscles were studied. During resting breathing, the duration of PIIA correlated with the duration of inspiration but not with expiration. Parasternal intercostal PIIA was directly related to that of the diaphragm. Based on their PIIA, dogs could be divided into two groups: one with prolonged PIIA (mean 0.57 s) and the other with brief PIIA (mean 0.16 s). Hypercapnia caused progressive shortening of the PIIA in the dogs with prolonged PIIA during resting breathing. The electrical activity of the external oblique and internal intercostal muscles increased gradually during CO2 rebreathing in all dogs both pre- and postvagotomy. After vagotomy, abdominal activity continued to increase with hypercapnia but was less at all levels of PCO2. The internal intercostal response to hypercapnia was not affected by vagotomy. The combination of shorter PIIA and augmented expiratory activity with hypercapnia might, in addition to changes in lung recoil pressure and airway resistance, hasten exhalation.

Ventilatory phase duration in the chicken: role of mechanical and CO2 feedback

1982 ◽  
Vol 53 (6) ◽  
pp. 1378-1385 ◽  
Author(s):  
G. O. Ballam ◽  
T. L. Clanton ◽  
A. L. Kunz
Keyword(s):  
Co2 Concentration ◽  
Gallus Domesticus ◽  
Negative Slope ◽  
Electromyographic Activity ◽  
Positive Slope ◽  
Phase Duration ◽  
Time Threshold ◽  
Expiratory Muscles ◽  
The Right

Awake upright White Leghorn roosters (Gallus domesticus) were unidirectionally ventilated. Electromyographic activity from inspiratory and expiratory muscles was recorded to demarcate inspiration and expiration. During inspiration, the rate of inflation of the air sac system was varied while the CO2 concentration of the gas passing through the lungs was maintained constant. Inspiratory duration was inversely related to the rate of inflation, producing an inspiratory volume-time threshold (VT) curve with a negative slope. When the CO2 concentration was increased in the lungs, the inspiratory VT curve shifted to the right with a concurrent increase in slope. If the rate of deflation was varied during expiration, it was found that expiratory duration was inversely related to the rate of deflation, producing an expiratory VT curve with a positive slope. Increasing the CO2 concentration shifted the curve to the left with an increased slope. These results indicate that inspiratory and expiratory phase durations are a function of both mechanical and chemical feedback.

Mechanical role of expiratory muscles during breathing in prone anesthetized dogs

1990 ◽  
Vol 69 (6) ◽  
pp. 2137-2142 ◽  
Author(s):  
G. A. Farkas ◽  
M. A. Schroeder
Keyword(s):  
Spontaneous Breathing ◽  
Muscle Activation ◽  
Transversus Abdominis ◽  
Emg Activity ◽  
Abdominal Muscles ◽  
Cervical Vagotomy ◽  
Anesthetized Dogs ◽  
Expiratory Muscles ◽  
External Oblique

The purpose of the present study was to assess the mechanical role of the expiratory muscles during spontaneous breathing in prone animals. The electromyographic (EMG) activity of the triangularis sterni, the rectus abdominis, the external oblique, and the transversus abdominis was studied in 10 dogs light anesthetized with pentobarbital sodium. EMGs were recorded during spontaneous steady-state breathing in supine and prone suspended animals both before and after cervical vagotomy. We also measured the end-expiratory lung volume [functional residual capacity (FRC)] in supine and prone positions to assess the mechanical role of expiratory muscle activation in prone dogs. Spontaneous breathing in the prone posture elicited a significant recruitment of the triangularis sterni, the external oblique, and the transversus abdominis (P less than 0.05). Bilateral cervical vagotomy eliminated the postural activation of the external oblique and the transversus abdominis but not the triangularis sterni. Changes in posture during control and after cervical vagotomy were associated with an increase in FRC. However, changes in FRC, on average, were 132.3 +/- 33.8 (SE) ml larger (P less than 0.01) postvagotomy. We conclude that spontaneous breathing in prone anesthetized dogs is associated with a marked phasic expiratory recruitment of rib cage and abdominal muscles. The present data also indicate that by relaxing at end expiration the expiratory muscles of the abdominal region are directly responsible for generating roughly 40% of the tidal volume.

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