After-Discharge in the Upper Airway Muscle Genioglossus Following Brief Hypoxia

SLEEP ◽  
2021 ◽  
Author(s):  
Joanne Avraam ◽  
Andrew Dawson ◽  
Nicole Feast ◽  
Feiven Lee Fan ◽  
Monika D Frigant ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Upper Airway ◽  
Motor Units ◽  
Firing Frequency ◽  
Healthy Individuals ◽  
Single Breath ◽  
Single Motor Units ◽  
Persistent Firing ◽  
Respiratory Modulation ◽  
Insight Into

Abstract Study Objectives Genioglossus after-discharge is thought to protect against pharyngeal collapse by minimising periods of low upper airway muscle activity. How genioglossus after-discharge occurs and which single motor units (SMUs) are responsible for the phenomenon are unknown. The aim of this study was to investigate genioglossal after-discharge. Methods During wakefulness, after-discharge was elicited 8-12 times in healthy individuals with brief isocapnic hypoxia (45-60s of 10%O2 in N2) terminated by a single breath of 100% O2. Genioglossus SMUs were designated as firing solely, or at increased rate, during inspiration (Inspiratory phasic [IP] and inspiratory tonic [IT] respectively); solely, or at increased rate, during expiration (Expiratory phasic [EP] or expiratory tonic [ET] respectively) or firing constantly without respiratory modulation (Tonic). SMUs were quantified at baseline, the end of hypoxia, the hyperoxic breath and the following 8 normoxic breaths. Results 210 SMU’s were identified in 17 participants. Genioglossus muscle activity was elevated above baseline for 7 breaths after hyperoxia (p<0.001), indicating a strong after-discharge effect. After-discharge occurred due to persistent firing of IP and IT units that were recruited during hypoxia, with minimal changes in ET, EP or Tonic SMUs. The firing frequency of units that were already active changed minimally during hypoxia or the afterdischarge period (P>0.05). Conclusion That genioglossal after-discharge is almost entirely due to persistent firing of previously silent inspiratory SMUs provides insight into the mechanisms responsible for the phenomenon and supports the hypothesis that the inspiratory and expiratory/tonic motor units within the muscle have idiosyncratic functions.

scholarly journals O037 Genioglossus motor control following the return to sleep after brief arousal

2021 ◽  
Vol 2 (Supplement_1) ◽  
pp. A16-A16
Author(s):  
A Dawson ◽  
J Avraam ◽  
C Nicholas ◽  
A Kay ◽  
J Trinder ◽  
...  
Keyword(s):  
Motor Units ◽  
Firing Frequency ◽  
Nasal Mask ◽  
Persistent Activity ◽  
Genioglossus Muscle ◽  
Single Motor Units ◽  
Airway Collapse ◽  
Obstructive Sleep ◽  
Persistent Firing ◽  
Healthy Participants

Abstract Rationale Arousal from sleep has been shown to elicit a prolonged increase in genioglossus muscle activity that persists following the return to sleep and may protect against airway collapse. We hypothesised that this increased genioglossal activity following return to sleep after an arousal is due to persistent firing of inspiratory single motor units (SMUs) recruited during the arousal. Methods 34 healthy participants were studied overnight while wearing a nasal mask/pneumotachograph to measure ventilation and with 4 intramuscular genioglossus SMU electrodes. During stable N2 and N3 sleep, auditory tones were played to induce brief (3-15s) AASM arousals. Ventilation and genioglossus SMUs were quantified for 5 breaths before the tone, during the arousal and for 10 breaths after the return to sleep. Results A total of 1089 tones were played and gave rise to 236 SMUs recorded across arousal and the return to sleep in 20 participants (age 23±4.2 years and BMI 22.5±2.2kg/m2). Ventilation was elevated above baseline during arousal and the first post-arousal breath (p<0.001). The peak firing frequency of expiratory and tonic SMUs was unchanged during arousal and return to sleep, whereas inspiratory modulated SMUs were increased during the arousal and for 4 breaths following the return to sleep (p<0.001). Conclusions The prolonged increase in genioglossus activity that occurs on return to sleep after arousal is a result of persistent activity of inspiratory SMUs. Strategies to elevate inspiratory genioglossus SMU activity may be beneficial in preventing/treating obstructive sleep apnea.

scholarly journals P005 The effect of alcohol on the motor control of the genioglossus muscle

2021 ◽  
Vol 2 (Supplement_1) ◽  
pp. A23-A23
Author(s):  
J Avraam ◽  
A Dawson ◽  
C Nicholas ◽  
A Kay ◽  
F O’Donoghue ◽  
...  
Keyword(s):  
Nasal Congestion ◽  
Upper Airway ◽  
Motor Units ◽  
Alcohol Concentration ◽  
Healthy Individuals ◽  
Depressant Effect ◽  
Genioglossus Muscle ◽  
Single Motor Units ◽  
Obstructive Sleep ◽  
Breath Alcohol Concentration

Abstract Rationale Alcohol is recognised to worsen snoring and obstructive sleep apnea (OSA). This effect is thought to be due to alcohol’s depressant effect on upper airway dilator muscles such as the genioglossus, but how alcohol reduces genioglossus activity is unknown. The aim of this study was to investigate alcohol’s effect on genioglossus single motor units (SMUs). Methods Healthy individuals visited the lab on two days (Alcohol: breath alcohol concentration ~0.08% or Placebo). They were instrumented with a nasal mask, 4 intramuscular genioglossus SMU EMG wires and an ear oximeter. They were exposed to 8–12 hypoxia trials (45-60s of 10%O2 followed by one breath of 100%O2) while awake. The SMUs were sorted according to their firing patterns with respect to respiration and were quantified during baseline, hypoxia, hyperoxia and recovery. Results The total number of SMUs recorded at baseline (68 and 67 respectively) and their distribution (ET: 29 vs 22, IP: 5 vs 10, IT: 8 vs 20 and TT: 26 vs 15 respectively) was similar between conditions. The discharge frequency did not differ between conditions (21Hz vs 22.4Hz, p>0.08). There was no difference between placebo and alcohol in the number (101 vs 88 respectively) and distribution (ET: 35 vs 32, IP: 22 vs 16, IT: 14 vs 22 and TT: 30 vs 17 respectively, p<0.05) of SMUs during hypoxia. Afterdischarge following hypoxia was also not different between conditions. Conclusion Alcohol has little effect on genioglossus SMUs and afterdischarge. OSA following alcohol may be related to increased upper airway resistance/nasal congestion.

Upper airway pressure receptors alter expiratory muscle EMG and motor unit firing

1988 ◽  
Vol 65 (1) ◽  
pp. 210-217 ◽  
Author(s):  
E. van Lunteren ◽  
N. S. Cherniack ◽  
T. E. Dick
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Upper Airway ◽  
Motor Units ◽  
Firing Frequency ◽  
Single Motor Unit ◽  
Expiratory Muscle ◽  
Motor Unit Activity ◽  
Motor Unit Firing ◽  
Respiratory Muscle Activity

To examine the effects of upper airway negative pressure (UAW NP) afferents on respiratory muscle activity during expiration (TE), diaphragm electromyograms (EMG) and triangularis sterni EMG and single motor unit activity were recorded from supine anesthetized tracheotomized cats while they breathed 100% O2. The period of TE during which the diaphragm was electrically active (TE-1) and the period of TE during which the diaphragm was quiescent (TE-2) were both increased with continuous UAW NP (P less than 0.001 and P less than 0.05, respectively), as was TE-1 as a percent of TE (P less than 0.001). Continuous UAW NP reduced peak triangularis sterni EMG (P less than 0.001) and delayed its expiratory onset (P less than 0.005) but did not alter its duration of firing. Changes in triangularis sterni EMG were due to a combination of complete cessation of motor unit activity (2 of 17 motor units), a reduction in mean motor unit firing frequency (P less than 0.02), and a delay in the expiratory onset of motor unit activity (P less than 0.001). Qualitatively similar results were obtained when UAW NP was applied during inspiration only. We conclude that 1) UAW NP has reciprocal stimulatory and inhibitory influences on diaphragm and triangularis sterni muscle electrical activity, respectively, during expiration, and 2) the reductions in triangularis sterni EMG are due to both motor unit derecruitment and a slowing of motor unit firing frequency.

scholarly journals Arousal from Sleep Does Not Lead to Reduced Dilator Muscle Activity or Elevated Upper Airway Resistance on Return to Sleep in Healthy Individuals

SLEEP ◽  
2015 ◽  
Vol 38 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Amy S. Jordan ◽  
Jennifer M. Cori ◽  
Andrew Dawson ◽  
Christian L. Nicholas ◽  
Fergal J. O'Donoghue ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Airway Resistance ◽  
Upper Airway ◽  
Healthy Individuals ◽  
Upper Airway Resistance ◽  
Dilator Muscle

Laryngeal muscle response to phasic and tonic upper airway pressure and flow

2001 ◽  
Vol 91 (2) ◽  
pp. 905-911 ◽  
Author(s):  
M. H. Stella ◽  
S. J. England
Keyword(s):  
Body Temperature ◽  
Muscle Activity ◽  
Upper Airway ◽  
Positive Pressure ◽  
Stimulus Modality ◽  
Respiratory Modulation ◽  
Temperature Constant ◽  
Posterior Cricoarytenoid ◽  
Spontaneously Breathing ◽  
Thyroarytenoid Muscle

The hypothesis that respiratory modulation due to upper airway (UA) pressure and flow is dependent on stimulus modality and respiratory phase-specific activation was assessed in anesthetized, tracheotomized, spontaneously breathing piglets. Negative pressure and flow applied to the isolated UA at room or body temperature during inspiration only enhanced posterior cricoarytenoid muscle activity from that present without UA pressure and flow (baseline) by 15–20%. Time shifting the onset of UA flow relative to tracheal flow decreased this enhancement. The same enhancement was observed with oscillatory or constant airflow. UA positive pressure and flow at room or body temperature applied during expiration only enhanced thyroarytenoid muscle activity from baseline by 50–160%. The same enhancement was observed with oscillatory or constant airflow at body temperature. Constant positive pressure and flow enhanced thyroarytenoid muscle activity more than oscillatory pressure and flow at room temperature. We conclude that the respiratory modulation of UA afferents is processed in a phase-specific fashion and is dependent on stimulus modality (tonic vs. phasic).

scholarly journals Mechanisms of the deep, slow-wave, sleep-related increase of upper airway muscle tone in healthy humans

2017 ◽  
Vol 122 (5) ◽  
pp. 1304-1312 ◽  
Author(s):  
Amelia Hicks ◽  
Jennifer M. Cori ◽  
Amy S. Jordan ◽  
Christian L. Nicholas ◽  
Leszek Kubin ◽  
...  
Keyword(s):  
Slow Wave ◽  
Muscle Activity ◽  
Airway Pressure ◽  
Slow Wave Sleep ◽  
Upper Airway ◽  
Sleep Stages ◽  
Healthy Individuals ◽  
Single Motor Unit ◽  
Central Chemoreceptors ◽  
Stimulation Of

Upper airway muscle activity is reportedly elevated during slow-wave sleep (SWS) when compared with lighter sleep stages. To uncover the possible mechanisms underlying this elevation, we explored the correlation between different indices of central and reflex inspiratory drive, such as the changes in airway pressure and end-expiratory CO2and the changes in the genioglossus (GG) and tensor palatini (TP) muscle activity accompanying transitions from the lighter N2 to the deeper N3 stage of non-rapid eye movement (NREM) sleep in healthy young adult men. Forty-six GG and 38 TP continuous electromyographic recordings were obtained from 16 men [age: 20 ± 2.5 (SD) yr; body mass index: 22.5 ± 1.8 kg/m2] during 32 transitions from NREM stages N2 to N3. GG but not TP activity increased following transition into N3 sleep, and the increase was positively correlated with more negative airway pressure, increased end-tidal CO2, increased peak inspiratory flow, and increased minute ventilation. None of these correlations was statistically significant for TP. Complementary GG and TP single motor unit analysis revealed a mild recruitment of GG units and derecruitment of TP units during the N2 to N3 transitions. These findings suggest that, in healthy individuals, the increased GG activity during SWS is driven primarily by reflex stimulation of airway mechanoreceptors and central chemoreceptors.NEW & NOTEWORTHY The characteristic increase in the activity of the upper airway dilator muscle genioglossus during slow-wave sleep (SWS) in young healthy individuals was found to be related to increased stimulation of airway mechanoreceptors and central chemoreceptors. No evidence was found for the presence of a central SWS-specific drive stimulating genioglossus activity in young healthy individuals. However, it remains to be determined whether a central drive exists in obstructive sleep apnea patients.

Spontaneous Electromyographic Activity in Adult Rat Soleus Muscle

1998 ◽  
Vol 80 (1) ◽  
pp. 365-376 ◽  
Author(s):  
Torsten Eken
Keyword(s):  
Motor Unit ◽  
Soleus Muscle ◽  
Motor Units ◽  
Firing Frequency ◽  
Electromyographic Activity ◽  
Single Motor Unit ◽  
Single Motor ◽  
Adult Rat ◽  
Single Motor Units ◽  
Rat Soleus Muscle

Eken, Torsten. Spontaneous electromyographic activity in adult rat soleus muscle. J. Neurophysiol. 80: 365–376, 1998. Single-motor-unit and gross electromyograms (EMG) were recorded from the soleus muscle in six unrestrained rats. The median firing frequencies of nine motor units were in the 16–25 Hz range, in agreement with previous studies. One additional motor unit had a median firing frequency of 47 Hz. This unit and one of the lower-frequency units regularly fired doublets. Motor-unit firing frequency was well correlated to whole-muscle EMG during locomotion. Integrated rectified gross EMG revealed periods of continuous modulation, phasic high-amplitude events, and tonic low-amplitude segments. The tonic segments typically were caused by a small number of motor units firing at stable high frequencies (20–30 Hz) for extended periods of time without detectable activity in other units. This long-lasting firing in single motor units typically was initiated by transient mass activity, which recruited many units. However, only one or a few units continued firing at a stable high frequency. The tonic firing terminated spontaneously or in conjunction with an episode of mass activity. Different units were active in different tonic segments. Thus there was an apparent dissociation between activity in different single motor units and consequently between single-motor-unit activity and whole-muscle EMG. It is proposed that the maintained tonic motor-unit activity is caused by intrinsic motoneuron properties in the form of depolarizing plateau potentials.

Phasic volume-related feedback on upper airway muscle activity

1984 ◽  
Vol 56 (3) ◽  
pp. 730-736 ◽  
Author(s):  
E. van Lunteren ◽  
K. P. Strohl ◽  
D. M. Parker ◽  
E. N. Bruce ◽  
W. B. Van de Graaff ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Phrenic Nerve ◽  
Muscle Activity ◽  
Moving Average ◽  
Upper Airway ◽  
Single Breath ◽  
Early Peak ◽  
Posterior Cricoarytenoid ◽  
Upper Airway Muscles ◽  
Spontaneously Breathing

The effects of vagally mediated volume-related feedback on the activity of upper airway muscles was assessed in nine pentobarbital-anesthetized, tracheostomized, spontaneously breathing dogs. Moving average electrical activity was recorded before and during single-breath airway occlusions from the genioglossus, posterior cricoarytenoid, and alae nasi muscles and compared with simultaneously recorded tidal volume and electrical activity of the phrenic nerve (6 dogs) or diaphragm (3 dogs). The normally early peak of upper airway muscle activity during unoccluded breaths was delayed to late or end inspiration during occluded breaths. Inspiratory depression started at a lower volume above end-expiratory volume and at an earlier time after inspiratory onset for the upper airway muscles than for the phrenic nerve and the diaphragm. The amount of depression at the end of inspiratory airflow was larger for all of the upper airway muscles than for the phrenic nerve and diaphragm. Depressive effects were most prominent in the genioglossus, followed by the posterior cricoarytenoid and the alae nasi. After vagotomy, depressive effects of volume-related feedback were no longer seen. These results suggest that activity of the upper airway muscles is modulated by vagally mediated feedback, apparently to a larger extent than that of the diaphragm and phrenic nerve.

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