scholarly journals Costal and crural diaphragm function during sustained hypoxia in awake canines

2019 ◽  
Vol 126 (4) ◽  
pp. 1117-1128 ◽  
Author(s):  
Tetsunori Ikegami ◽  
Michael Ji ◽  
Naoyuki Fujimura ◽  
Jenny V. Suneby Jagers ◽  
Teresa M. Kieser ◽  
...  
Keyword(s):  
Muscle Length ◽  
Mechanical Action ◽  
Emg Activity ◽  
Initial Increase ◽  
Neural Activation ◽  
Biphasic Pattern ◽  
Diaphragmatic Function ◽  
Diaphragm Function ◽  
Crural Diaphragm ◽  
Sustained Hypoxia

In humans and other mammals, isocapnic hypoxia sustained for 20–60 min exhibits a biphasic ventilation pattern: initial increase followed by a significant ventilatory decline (“roll-off”) to a lesser intermediate plateau. During sustained hypoxia, the mechanical action and activity of the diaphragm have not been studied; thus we assessed diaphragm function in response to hypoxic breathing. Thirteen spontaneously breathing awake canines were exposed to moderate levels of sustained isocapnic hypoxia lasting 20–25 min (80 ± 2% pulse oximeter oxygen saturation). Breathing pattern and changes in muscle length and electromyogram (EMG) activity of the costal and crural diaphragm were continuously recorded. Mean tidal shortening and EMG activity of the costal and crural diaphragm exhibited an overall biphasic pattern, with initial brisk increase followed by a significant decline ( P < 0.01). Although costal and crural shortening did not differ significantly with sustained hypoxia, this equivalence in segmental shortening occurred despite distinct and differing EMG activities of the costal and crural segments. Specifically, initial hypoxia elicited a greater costal EMG activity compared with crural ( P < 0.05), whereas sustained hypoxia resulted in a lesser crural EMG decline/attenuation than costal ( P < 0.05). We conclude that sustained isocapnic hypoxia elicits a biphasic response in both ventilation and diaphragmatic function and there is clear differential activation and contribution of the two diaphragmatic segments. This different diaphragm segmental action is consistent with greater neural activation of costal diaphragm during initial hypoxia, then preferential sparing of crural activation as hypoxia is sustained. NEW & NOTEWORTHY In humans and other mammals, during isocapnic hypoxia sustained for 20–60 min ventilation exhibits a biphasic pattern: initial increase followed by significant ventilatory decline (“roll-off”). During sustained hypoxia, the function of the diaphragm is unknown. This study demonstrates that the diaphragm reveals a biphasic action during the time-dependent hypoxic “roll-off” in ventilation. These results also highlight that the two diaphragm segments, costal and crural, show differing, distinctive contributions to diaphragm function during sustained hypoxia.

scholarly journals Geniohyoid muscle function in awake canines

2003 ◽  
Vol 95 (2) ◽  
pp. 810-817 ◽  
Author(s):  
M. Yokoba ◽  
H. G. Hawes ◽  
P. A. Easton
Keyword(s):  
Muscle Function ◽  
Breathing Pattern ◽  
Muscle Length ◽  
Upper Airway ◽  
Mechanical Action ◽  
Emg Activity ◽  
Airway Occlusion ◽  
Lateral Decubitus ◽  
The Right ◽  
Emg Electrodes

The geniohyoid (Genio) upper airway muscle shows phasic, inspiratory electrical activity in awake humans but no activity and lengthening in anesthetized cats. There is no information about the mechanical action of the Genio, including length and shortening, in any awake, nonanesthetized mammal during respiration (or swallowing). Therefore, we studied four canines, mean weight 28.8 kg, 1.5 days after Genio implantation with sonomicrometry transducers and bipolar electromyogram (EMG) electrodes. Awake recordings of breathing pattern, muscle length and shortening, and EMG activity were made with the animal in the right lateral decubitus position during quiet resting, CO2-stimulated breathing, inspiratory-resisted breathing (80 cmH2O · l-1 · s), and airway occlusion. Genio length and activity were also measured during swallowing, when it shortened, showing a 9.31% change from resting length, and its EMG activity increased 6.44 V. During resting breathing, there was no phasic Genio EMG activity at all, and Genio showed virtually no movement during inspiration. During CO2-stimulated breathing, Genio showed minimal lengthening of only 0.07% change from resting length, whereas phasic EMG activity was still absent. During inspiratory-resisted breathing and airway occlusion, Genio showed phasic EMG activity but still lengthened. We conclude that the Genio in awake, nonanesthetized canines shows active contraction and EMG activity only during swallowing. During quiet or stimulated breathing, Genio is electrically inactive with passive lengthening. Even against resistance, Genio is electrically active but still lengthens during inspiration.

Parasternal Intercostal, Costal and Crural Diaphragm Neural Activation During Hypercapnia

2021 ◽  
Author(s):  
Giovanni Tagliabue ◽  
Michael Sukjoon Ji ◽  
Jenny V. Suneby Jagers ◽  
Dan J. Zuege ◽  
John B. Kortbeek ◽  
...  
Keyword(s):  
Chest Wall ◽  
Mechanical Action ◽  
Baseline Length ◽  
Neural Activation ◽  
Common Pathway ◽  
Non Invasive ◽  
Clinical Interest ◽  
Crural Diaphragm ◽  
Spontaneously Breathing ◽  
Similar Intensity

Background Parasternal intercostal is an obligatory inspiratory muscle working in coordination with the diaphragm, apparently sharing a common pathway of neural response. This similarity has attracted clinical interest, promoting parasternal as a non-invasive alternative to the diaphragm, to monitor central neural respiratory output. However, this role may be confounded by the distinct and different functions of costal and crural diaphragm. Given the anatomic location, parasternal activation may significantly impact chest wall via both mechanical shortening or as a "fixator" for the chest wall. Either mechanical function of parasternal may also impact differential function of costal and crural. Objectives During eupnea and hypercapnia, 1) compare the intensity of neural activation of parasternal, with costal and crural diaphragm; 2)examine parasternal recruitment and changes in mechanical action during progressive hypercapnia, including muscle baseline length and shortening. Methods In 30 spontaneously breathing canines, awake without confounding anesthetic, we measured directly both electrical activity of parasternal, costal, and crural diaphragm, and corresponding mechanical shortening of parasternal, during eupnea and hypercapnia. Results During eupnea and hypercapnia, parasternal and costal diaphragm share a similar intensity of neural activation, while both differ significantly from crural diaphragm activity. The shortening of parasternal increases significantly with hypercapnia, without change in baseline end-expiratory length. Conclusion Parasternal shares an equivalent intensity of neural activation with costal, but not crural, diaphragm. Parasternal maintains and increases its active inspiratory shortening during augmented ventilation, despite high levels of diaphragm recruitment. Throughout hypercapnic ventilation, parasternal contributes mechanically - it is not relegated to chest wall fixation.

Costal and crural diaphragm function during CO2 rebreathing in awake dogs

1993 ◽  
Vol 74 (3) ◽  
pp. 1406-1418 ◽  
Author(s):  
P. A. Easton ◽  
J. W. Fitting ◽  
R. Arnoux ◽  
A. Guerraty ◽  
A. E. Grassino
Keyword(s):  
Inspiratory Flow ◽  
Emg Activity ◽  
Co2 Rebreathing ◽  
Diaphragm Function ◽  
Inspiratory Activity ◽  
Crural Diaphragm ◽  
Emg Electrodes ◽  
Segmental Function

If costal and crural diaphragm segments can perform as separate muscles, then CO2-stimulated ventilation may elicit differential segmental function. We studied diaphragm segmental length, shortening, and electromyogram (EMG) activity in 10 awake dogs chronically implanted with sonomicrometer transducers and EMG electrodes. During CO2 rebreathing, segmental shortening and EMG activity per whole tidal breath progressively increased, but segmental responses could not be differentiated at any level of CO2. With increasing CO2, resting end-expiratory length of both diaphragm segments increased. During the complete intrabreath inspiratory-expiratory cycle, costal and crural diaphragm revealed distinctive segmental function. At rest, crural shortening exceeded costal shortening in earliest inspiration, costal and especially crural shortening persisted into early expiration, and EMG activity of the crural segment was greater than that of the costal segment in earliest inspiration and showed more end-inspiratory/early expiratory [post-inspiratory inspiratory activity (PIIA)] activity. During CO2-stimulated breathing, neither segment shortened during the inspiratory flow of earliest inspiration. During CO2 rebreathing, shortening of the crural segment exceeded that of the costal segment during early inspiration and outlasted costal shortening during expiration; for both segments, shortening persisted after termination of inspiratory airflow. With increased CO2, EMG activity of the crural segment preceded that of the costal segment in earliest inspiration and was dominant into expiration, whereas costal EMG activity terminated abruptly with inspiratory flow. Thus, costal EMG PIIA was not evident during hypercapnia, whereas crural EMG PIIA was significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Velocity of shortening of inspiratory muscles and inspiratory flow

1986 ◽  
Vol 60 (2) ◽  
pp. 670-677 ◽  
Author(s):  
J. W. Fitting ◽  
P. A. Easton ◽  
A. E. Grassino
Keyword(s):  
Muscle Length ◽  
Linear Increase ◽  
Inspiratory Flow ◽  
Emg Activity ◽  
Mean Velocity ◽  
Co2 Partial Pressure ◽  
Inspiratory Muscles ◽  
Velocity Of Shortening ◽  
Anesthetized Dogs ◽  
Crural Diaphragm

Respiratory muscle length was measured with sonomicrometry to determine the relation between inspiratory flow and velocity of shortening of the external intercostal and diaphragm. Electromyographic (EMG) activity and tidal shortening of the costal and crural segments of the diaphragm and of the external intercostal were recorded during hyperoxic CO2 rebreathing in 12 anesthetized dogs. We observed a linear increase of EMG activity and peak tidal shortening of costal and crural diaphragm with alveolar CO2 partial pressure. For the external intercostal, no consistent pattern was found either in EMG activity or in tidal shortening. Mean inspiratory flow was linearly related to mean velocity of shortening of costal and crural diaphragm, with no difference between the two segments. Considerable shortening occurred in costal and crural diaphragm during inspiratory efforts against occlusion. We conclude that the relation between mean inspiratory flow and mean velocity of shortening of costal and crural diaphragm is linear and can be altered by an inspiratory load. There does not appear to be a relationship between inspiratory flow and velocity of shortening of external intercostals.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Muscle dynamics in skipjack tuna: timing of red muscle shortening in relation to activation and body curvature during steady swimming

1999 ◽  
Vol 202 (16) ◽  
pp. 2139-2150 ◽  
Author(s):  
R.E. Shadwick ◽  
S.L. Katz ◽  
K.E. Korsmeyer ◽  
T. Knower ◽  
J.W. Covell
Keyword(s):  
Fork Length ◽  
Muscle Length ◽  
The Body ◽  
Emg Activity ◽  
Skipjack Tuna ◽  
Force Transmission ◽  
Muscle Strain ◽  
Muscle Shortening ◽  
Red Muscle ◽  
Length Changes

Cyclic length changes in the internal red muscle of skipjack tuna (Katsuwonus pelamis) were measured using sonomicrometry while the fish swam in a water tunnel at steady speeds of 1.1-2.3 L s(−)(1), where L is fork length. These data were coupled with simultaneous electromyographic (EMG) recordings. The onset of EMG activity occurred at virtually the same phase of the strain cycle for muscle at axial locations between approximately 0.4L and 0.74L, where the majority of the internal red muscle is located. Furthermore, EMG activity always began during muscle lengthening, 40–50 prior to peak length, suggesting that force enhancement by stretching and net positive work probably occur in red muscle all along the body. Our results support the idea that positive contractile power is derived from all the aerobic swimming muscle in tunas, while force transmission is provided primarily by connective tissue structures, such as skin and tendons, rather than by muscles performing negative work. We also compared measured muscle length changes with midline curvature (as a potential index of muscle strain) calculated from synchronised video image analysis. Unlike contraction of the superficial red muscle in other fish, the shortening of internal red muscle in skipjack tuna substantially lags behind changes in the local midline curvature. The temporal separation of red muscle shortening and local curvature is so pronounced that, in the mid-body region, muscle shortening at each location is synchronous with midline curvature at locations that are 7–8 cm (i.e. 8–10 vertebral segments) more posterior. These results suggest that contraction of the internal red muscle causes deformation of the body at more posterior locations, rather than locally. This situation represents a unique departure from the model of a homogeneous bending beam, which describes red muscle strain in other fish during steady swimming, but is consistent with the idea that tunas produce thrust by motion of the caudal fin rather than by undulation of segments along the body.

Effect of quadriceps femoris muscle length on neural activation during isometric and concentric contractions

2003 ◽  
Vol 94 (3) ◽  
pp. 983-990 ◽  
Author(s):  
Nicolas Babault ◽  
Michel Pousson ◽  
Anne Michaut ◽  
Jacques Van Hoecke
Keyword(s):  
Knee Flexion ◽  
Muscle Length ◽  
Isometric Contractions ◽  
Neural Activation ◽  
Length Effect ◽  
Neural Drive ◽  
Concentric Contractions ◽  
Twitch Interpolation ◽  
Predominant Effect ◽  
Femoris Muscle

The effect of muscle length on neural drive (here termed “neural activation”) was investigated from electromyographic activities and activation levels (twitch interpolation). The neural activation was measured in nine men during isometric and concentric (30 and 120°/s) knee extensions for three muscle lengths (35, 55, and 75° knee flexion, i.e., shortened, intermediate, and lengthened muscles, respectively). Long (76°), medium (56°), and short (36°) ranges of motion were used to investigate the effect of the duration of concentric contraction. Neural activation was found to depend on muscle length. Reducing the duration of contraction had no effect. Neural activation was higher with short muscle length during isometric contractions and was weaker for shortened than for intermediate and lengthened muscles performing 120°/s concentric contractions. Muscle length had no effect on 30°/s concentric neural activation. Peripheral mechanisms and discharge properties of the motoneurons could partly explain the observed differences in the muscle length effect. We thus conclude that muscle length has a predominant effect on neural activation that would modulate the angular velocity dependency.

Activation in frog atrial trabeculae: dependence on temperature and length

1990 ◽  
Vol 258 (4) ◽  
pp. H1087-H1096
Author(s):  
P. J. Reiser ◽  
B. D. Lindley
Keyword(s):  
Stimulus Frequency ◽  
Muscle Length ◽  
Initial Increase ◽  
Initial Tension ◽  
Tension Development ◽  
Temperature Jumps ◽  
Rapid Temperature ◽  
Tension Increase ◽  
Cross Bridges ◽  
Tension Transients

Isolated frog atrial trabeculae were activated using the method of Na+ withdrawal to induce contractures of relatively steady tension. External Na+ concentration [( Na+]o) during contractures was varied between 0.25 and 45 mM. Isometric contracture tension was measured at cold (4 degrees C) and warm (20 degrees C) temperatures. In addition, rapid temperature jumps (complete in approximately 400 ms) were imposed during cold contractures, resulting in tension transients that consisted of an initial increase in tension followed by a decrease, the latter phase being greater at small and moderate reductions in [Na+]o. Peak contracture tension varied with relative muscle length. The trabeculae became more sensitive with stretch to Na+ withdrawal at 20 degrees C and generated relatively greater tensions at a given [Na+]o. The initial tension increase after a temperature jump was directly proportional to the peak contracture tension immediately preceding the increase in temperature and was therefore interpreted as reflecting an effect of the higher temperature on the attached force-generating cross bridges. The effects of cold and warm steady temperatures and temperature jumps during isometric twitches were also studied. Peak twitch tension varied inversely with temperature (stimulus frequency = 0.2 Hz). In contrast, temperature jumps imposed during the rising phase of twitches at a steady cold temperature (approximately 4 degrees C) resulted in a large initial increase in tension followed by relaxation at a rate that was characteristic of the elevated temperature. The results suggest that, at the warmer temperature (approximately 20 degrees C), activation (i.e., number of attached cross bridges) of the myocardium is significantly less than maximal during the twitch response. The dependence of the tension vs. [Na+]o curves and the tension transients resulting from the temperature jumps on relative muscle length provide evidence for a length dependency of contractile activation in intact atrial trabeculae under conditions of steady-state tension development.

Tonic and Phasic Discharge Patterns in Toe Flexor γ-Motoneurons During Locomotion in the Decerebrate Cat

2002 ◽  
Vol 87 (1) ◽  
pp. 286-294 ◽  
Author(s):  
P. R. Murphy
Keyword(s):  
Mechanical Action ◽  
Emg Activity ◽  
Flexor Hallucis Longus ◽  
Plantar Flexor ◽  
Step Cycle ◽  
Decerebrate Cat ◽  
Hindlimb Muscles ◽  
Discharge Patterns ◽  
Flexor Digitorum ◽  
Α Activity

To investigate the specificity of fusimotor (γ) drive during locomotion, γ-efferents were recorded from the flexor digitorum longus (FDL) and flexor hallucis longus (FHL) nerves in a decerebrate cat preparation. These nerves innervate hindlimb muscles that differ in some aspects of their mechanical action. For both FHL and FDL two stereotyped patterns of γ activity were distinguished. Tonic units fired throughout the step cycle and had less modulation, but higher minimum rates, than phasic units, which were mainly recruited with ankle extensor [soleus (SOL)] electromyogram (EMG) activity. Differences in the relative timing of these patterns were apparent. In FHL the activity of phasic and most tonic neurons peaked after EMG onset. With FDL, tonic units generally reached maximum rate before, while phasic units peaked after, the beginning of EMG activity. During locomotion FHL and FDL α activity were rhythmically recruited with SOL. However, consistent with previous reports, FHL and FDL differed in their patterns of α activity. FHL was stereotyped while FDL was variable. Both FHL and FDL had activity related to ankle extensor EMG, but only FDL exhibited a peak around the end of this phase. No corresponding γ activity was observed in FDL. In conclusion, 1) FHL and FDL received tonic and phasic fusimotor drive; 2) there was no α/γ linkage for the late FDL α burst; 3) phasic γ-efferents in both muscles received similar inputs, linked to plantar flexor α activity; and 4) tonic γ-efferents differed, to the extent that they were modulated at all. The FHL units peaked with the plantar flexor alphas. The FDL neurons generally peaked before α activity even began.

In vivo regional diaphragm function in dogs

1989 ◽  
Vol 67 (2) ◽  
pp. 655-662 ◽  
Author(s):  
J. Sprung ◽  
C. Deschamps ◽  
R. D. Hubmayr ◽  
B. J. Walters ◽  
J. R. Rodarte
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Spontaneous Breathing ◽  
Considerable Variability ◽  
Diaphragm Function ◽  
Left Hemidiaphragm ◽  
Anesthetized Dogs ◽  
Abdominal Surface ◽  
Crural Diaphragm

A biplane videofluorographic system was used to track the position of metallic markers affixed to the abdominal surface of the left hemidiaphragm in supine anesthetized dogs. Regional shortening was determined from intermarker distances of rows of markers placed along muscle bundles in the ventral, middle, and dorsal regions of the costal diaphragm and of one row on the crural diaphragm. Considerable variability of regional shortening was seen in a given row, which was reproducible on repeat study in individual dogs but which differed between mechanical ventilation and spontaneous breathing. There were no consistent patterns among dogs. Regional shortening obtained from the change in length of rows extending from chest wall to central tendon showed no consistent differences among dogs during spontaneous breathing. At equal tidal volumes, all regions (except the ventral costal diaphragm) shortened more during spontaneous breathing than during mechanical ventilation.

Sign in / Sign up

Export Citation Format

Share Document