scholarly journals Differential respiratory muscle recruitment induced by clonidine in awake goats

1998 ◽  
Vol 84 (4) ◽  
pp. 1198-1207 ◽  
Author(s):  
Michael S. Hedrick ◽  
Melinda R. Dwinell ◽  
Patrick L. Janssen ◽  
Josue Pizarro ◽  
Gerald E. Bisgard
Keyword(s):  
Respiratory Muscle ◽  
Respiratory Muscles ◽  
Upper Airway ◽  
Transversus Abdominis ◽  
Muscle Recruitment ◽  
Breathing Cycle ◽  
Peripheral Chemoreceptor ◽  
Inspiratory Muscles ◽  
Tonic Activation ◽  
Expiratory Muscles

The purpose of this study was to test the hypothesis that dysrhythmic breathing induced by the α2-agonist clonidine is accompanied by differential recruitment of respiratory muscles. In adult goats ( n = 14) electromyographic (EMG) measurements were made from inspiratory muscles (diaphragm and parasternal intercostal) and expiratory muscles [triangularis sterni (TS) and transversus abdominis (Abd)]. EMG of the thyroarytenoid (TA) muscle was used as an index of upper airway (glottal) patency. Peak EMG activities of all spinal inspiratory and expiratory muscles were augmented by central and peripheral chemoreceptor stimuli. Phasic TA was apparent in the postinspiratory phase of the breathing cycle under normoxic conditions. During dysrhythmic breathing episodes induced by clonidine, TS and Abd activities were attenuated or abolished, whereas diaphragm and parasternal intercostal activities were unchanged. There was no tonic activation of TS or Abd EMG during apneas; however, TA activity became tonic throughout the apnea. We conclude that 1) α2-adrenoceptor stimulation results in differential recruitment of respiratory muscles during respiratory dysrhythmias and 2) apneas are accompanied by active glottic closure in the awake goat.

Respiratory Muscle Interaction

Physiology ◽  
1993 ◽  
Vol 8 (3) ◽  
pp. 121-124 ◽  
Author(s):  
M Decramer
Keyword(s):  
Chest Wall ◽  
Respiratory Muscle ◽  
Respiratory Muscles ◽  
Transversus Abdominis ◽  
Quiet Breathing ◽  
Expiratory Muscles

Breathing requires a coordinated contraction of different respiratory muscles. During quiet breathing in upright humans, the diaphragm, parasternal intercostals, and scalenes contract and interact to displace the chest wall along its relaxation line. The most important expiratory muscles, triangularis sterni and transversus abdominis, do not contribute to quiet breathing.

Force potentiation in respiratory muscles: comparison of diaphragm and sternohyoid

1993 ◽  
Vol 264 (6) ◽  
pp. R1095-R1100 ◽  
Author(s):  
E. Van Lunteren ◽  
H. Vafaie
Keyword(s):  
Respiratory Muscle ◽  
Respiratory Muscles ◽  
Upper Airway ◽  
Rapid Onset ◽  
Force Frequency ◽  
Twitch Force ◽  
Twitch Potentiation ◽  
Early Portion ◽  
Frequency Relationship

Coordinated contraction of thoracic and pharyngeal upper airway respiratory muscles optimizes ventilation, whereas pharyngeal muscle dysfunction may lead to obstructive apneas during sleep. We hypothesized that the force potentiation exhibited by the pharyngeal respiratory muscle, the sternohyoid, in keeping with its faster contractile kinetics, would be greater than that of the thoracic respiratory muscle, the diaphragm. Rat muscles were studied in vitro at 37 degrees C with three force-potentiating protocols: posttetanic twitch potentiation, staircase phenomenon (twitch potentiation), and a classic fatigue paradigm. The sternohyoid had a faster isometric contraction time, a more rightward located force-frequency relationship, and both a more rapid onset and a greater degree of fatigue than the diaphragm. During the early portion of the fatigue protocols, the increase in force was significantly greater for the sternohyoid muscle than the diaphragm (e.g., 33 vs. 3% increase at 20 Hz, P < 0.005). During repetitive twitches at 2, 3, and 5 Hz (staircase test), sternohyoid muscle force increased more than diaphragm force at the higher stimulus frequencies (e.g., by 38 vs. 23% at 5 Hz, P < 0.01). After brief tetanic stimuli, sternohyoid twitch force increased more than diaphragm twitch force (e.g., 73 vs. 14% increase after 125 Hz tetanus, P < 0.005). These data indicate that force potentiation is exhibited by both diaphragm and sternohyoid respiratory muscles, but to different extents, when activated repetitively.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory muscle responses to changes in chemoreceptor drive in infants

1990 ◽  
Vol 68 (3) ◽  
pp. 1041-1047 ◽  
Author(s):  
W. A. Carlo ◽  
J. M. DiFiore
Keyword(s):  
Preterm Infants ◽  
Respiratory Muscle ◽  
Muscle Activation ◽  
Respiratory Muscles ◽  
Upper Airway ◽  
Obstructive Apnea ◽  
Surface Electrodes ◽  
Posterior Cricoarytenoid ◽  
Upper Airway Muscles ◽  
Muscle Responses

Upper airway muscles and the diaphragm may have different quantitative responses to chemoreceptor stimulation. To compare the respiratory muscle responses to changes in CO2, 10 ventilator-dependent preterm infants (gestational age 28 +/- 1 wk, postnatal age 40 +/- 6 days, weight 1.4 +/- 0.1 kg) were passively hyperventilated to apnea and subsequently hypoventilated. Electromyograms from the genioglossus, alae nasi, posterior cricoarytenoid, and diaphragm were recorded from surface electrodes. Apneic CO2 thresholds of all upper airway muscles (genioglossus 46.8 +/- 4.3 Torr, alae nasi 42.4 +/- 3.6 Torr, posterior cricoarytenoid 41.6 +/- 3.2 Torr) were higher than those of the diaphragm (38.8 +/- 2.6 Torr, all P less than 0.05). Above their CO2 threshold levels, responses of all upper airway muscles appeared proportional to those of the diaphragm. We conclude that nonproportional responses of the respiratory muscles to hypercapnia may be the result of differences in their CO2 threshold. These differences in CO2 threshold may cause imbalance in respiratory muscle activation with changes in chemical drive, leading to upper airway instability and obstructive apnea.

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.

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.

Reflex effect of esophageal distension on respiratory muscle activity and pressure

1989 ◽  
Vol 66 (2) ◽  
pp. 536-541 ◽  
Author(s):  
A. Oliven ◽  
M. Haxhiu ◽  
S. G. Kelsen
Keyword(s):  
Motor Activity ◽  
Electrical Activity ◽  
Respiratory Muscle ◽  
Abdominal Cavity ◽  
Respiratory Muscles ◽  
Abdominal Pressure ◽  
Lung Inflation ◽  
Rib Cage ◽  
Expiratory Muscles ◽  
Crural Diaphragm

The electrical activity of the respiratory skeletal muscles is altered in response to reflexes originating in the gastrointestinal tract. The present study evaluated the reflex effects of esophageal distension (ED) on the distribution of motor activity to both inspiratory and expiratory muscles of the rib cage and abdomen and the resultant changes in thoracic and abdominal pressure during breathing. Studies were performed in 21 anesthetized spontaneously breathing dogs. ED was produced by inflating a balloon in the distal esophagus. ED decreased the activity of the costal and crural diaphragm and external intercostals and abolished all preexisting electrical activity in the expiratory muscles of the abdominal wall. On the other hand, ED increased the activity of the parasternal intercostals and expiratory muscles located in the rib cage (i.e., triangularis sterni and internal intercostal). All effects of ED were graded, with increasing distension exerting greater effects, and were eliminated by vagotomy. The effect of increases in chemical drive and lung inflation reflex activity on the response to ED was examined by performing ED while animals breathed either 6.5% CO2 or against graded levels of positive end-expiratory pressure (PEEP), respectively. Changes in respiratory muscle electrical activity induced by ED were similar (during 6.5% CO2 and PEEP) to those observed under control conditions. We conclude that activation of mechanoreceptors in the esophagus reflexly alters the distribution of motor activity to the respiratory muscles, inhibiting the muscles surrounding the abdominal cavity and augmenting the parasternals and expiratory muscles of the chest wall.

Relation between work output of respiratory muscles and end-tidal CO2 tension

1963 ◽  
Vol 18 (3) ◽  
pp. 497-504 ◽  
Author(s):  
J. Milic-Emili ◽  
J. M. Tyler
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Ventilation ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Work Output ◽  
Inspiratory Muscles ◽  
Expiratory Muscles ◽  
End Tidal ◽  
End Tidal Co2

End-tidal CO2 tension, pulmonary ventilation, and work output of respiratory muscles were determined in six normal subjects breathing various mixtures of carbon dioxide in air, with three graded resistances added to both inspiration and expiration. In two individuals, the resistances were also added separately to inspiration or expiration. A linear relationship was found between work output of inspiratory muscles and end-tidal CO2 tension; this relationship was uninfluenced by added resistance. No consistent relationship was observed between either ventilation or work output of expiratory muscles and end-tidal CO2 tension. These results suggest that carbon dioxide controls directly the activity of inspiratory muscles alone and that the activity of expiratory muscles is only coincidentally involved. The possible role of intrinsic properties of respiratory muscles and of nervous mediation in the control of breathing is discussed. Submitted on October 22, 1962

Variations in respiratory muscle activity during echolocation when stationary in three species of bat (Microchiroptera: Vespertilionidae)

2001 ◽  
Vol 204 (24) ◽  
pp. 4185-4197
Author(s):  
Winston C. Lancaster ◽  
J. R. Speakman
Keyword(s):  
Muscle Activity ◽  
Respiratory Muscle ◽  
Respiratory Muscles ◽  
Transversus Abdominis ◽  
Abdominal Muscles ◽  
Pteronotus Parnellii ◽  
Economic Production ◽  
Morphological Adaptations ◽  
The Family ◽  
Respiratory Muscle Activity

SUMMARY Echolocating bats use respiratory muscles to power the production of biosonar vocalisations. The physical characteristics of these calls vary among species of bat, and variations also exist in the timing and patterns of respiratory muscle recruitment during echolocation. We recorded electromyograms from the respiratory muscles of three species of bat (Family Vespertilionidae) while the animals vocalised from stationary positions. Activity was recorded consistently from the lateral abdominal muscles (internal abdominal oblique and transversus abdominis) from all calling bats, but we found much variation within and among species. Bats in the family Vespertilionidae devoted longer periods of expiratory muscle activity to each call than did the mormoopid bat Pteronotus parnellii. These differences correlate negatively with the duration of calls. We suggest that morphological adaptations in some bats may facilitate the economic production of echolocation calls at rest.

Effects of aging and obesity on respiratory muscle phenotype in Zucker rats

1996 ◽  
Vol 81 (3) ◽  
pp. 1347-1354 ◽  
Author(s):  
S. K. Powers ◽  
G. A. Farkas ◽  
H. Demirel ◽  
J. Coombes ◽  
L. Fletcher ◽  
...  
Keyword(s):  
Respiratory Muscle ◽  
Citrate Synthase ◽  
Work Of Breathing ◽  
Age Groups ◽  
Respiratory Muscles ◽  
Oxidative Capacity ◽  
Zucker Rats ◽  
Type I ◽  
Inspiratory Muscles ◽  
Age Related

Because obesity results in an increased work of breathing, we tested the hypothesis that the oxidative properties and myosin heavy chain (MHC) isoform profiles in respiratory muscles would differ between lean and obese animals. Furthermore, we postulated that obesity-related changes in respiratory muscles would be independent of age. To test these hypothesis, samples of the costal diaphragm, crural diaphragm, and parasternal intercostal muscles were removed from three age groups (young, adult, and old) of obese and lean Zucker rats. Citrate synthase (CS) activity was measured as a marker of oxidative capacity, and MHC isoforms were identified with gel electrophoresis. Analysis revealed that CS activity was significantly higher in the crural and costal diaphragms and parasternal intercostal of obese animals compared with lean animals (P < 0.05); this obesity-related increased in CS activity was related independent of age. Furthermore, respiratory muscle percent type IIb MHC was lower and percent type I MHC isoforms were higher in obese animals compared with lean animals. These data support the notion that obesity results in a fast-to-slow shift in MHC phenotype and an increase in oxidative capacity in major inspiratory muscles. The shift in MHC isoforms in obese animals is also age related, whereas the obesity-mediated increase in oxidative capacity is relatively independent of age.

Respiratory muscle control during vomiting

1990 ◽  
Vol 68 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Alan D. Miller
Keyword(s):  
Response Pattern ◽  
Respiratory Muscles ◽  
Respiratory Neurons ◽  
Abdominal Muscles ◽  
Inspiratory Muscles ◽  
Medullary Respiratory Neurons ◽  
Gastric Contents ◽  
Expiratory Neurons ◽  
Expiratory Muscles ◽  
Thoracic And Abdominal

The changes in thoracic and abdominal pressures that generate vomiting are produced by coordinated action of the major respiratory muscles. During vomiting, the diaphragm and external intercostal (inspiratory) muscles co-contract with abdominal (expiratory) muscles in a series of bursts of activity that culminates in expulsion. Internal intercostal (expiratory) muscles contract out of phase with these muscles during retching and are inactive during expulsion. The periesophageal portion of the diaphragm relaxes during expulsion, presumably facilitating rostral movement of gastric contents. Recent studies have begun to examine to what extent medullary respiratory neurons are involved in the control of these muscles during vomiting. Bulbospinal expiratory neurons in the ventral respiratory group caudal to the obex discharge at the appropriate time during (fictive) vomiting to activate either abdominal or internal intercostal motoneurons. The pathways that drive phrenic and external intercostal motoneurons during vomiting have yet to be identified. Most bulbospinal inspiratory neurons in the dorsal and ventral respiratory groups do not have the appropriate response pattern to initiate activation of these motoneurons during (fictive) vomiting. Relaxation of the periesophageal diaphragm during vomiting could be brought about, at least in part, by reduced firing of bulbospinal inspiratory neurons.Key words: brain stem, bulbospinal respiratory neurons, vomiting center critique, diaphragm, abdominal muscles.

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