Responses of upper airway, intercostal and diaphragm muscle activity to stimulation of oesophageal afferents in dogs.

Cherniack, Neil S.; Haxhiu, Musa A.; Mitra, J.; Lunteren, Erik van

doi:10.1113/jphysiol.1984.sp015139

Cited by 40 publications

(28 citation statements)

References 9 publications

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“…Although the majority of studies on TLESR have been conducted in humans, the phenomenon has been recorded in dogs (6,11,18), cats, and ferrets (3). The LES relaxation is the major criterion for identification of TLESR in the human as well as animal studies (10).…”

Section: Discussionmentioning

confidence: 99%

Baclofen blocks LES relaxation and crural diaphragm inhibition by esophageal and gastric distension in cats

Liu

Pehlivanov

Mittal

2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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Recent studies indicate that baclofen decreases the frequency of TLESR; however, its effect on the crural diaphragm is not known. We evaluated the effects of baclofen on LES relaxation and crural diaphragm inhibition induced by gastric distension and esophageal distension in cats. Five adult cats underwent surgical implantation of wire electrodes into the crural and costal diaphragm for measurement of their EMG activity, respectively. One week after the surgery, animals were lightly sedated and recordings were performed using a manometry catheter equipped with a 2.5-cm balloon. The effects of baclofen (10 mol/kg iv) on the graded esophageal distension and gastric distension-induced LES and crural diaphragm responses were studied. Distension of the esophagus and stomach induces relaxation of the LES and inhibition of the crural diaphragm, simultaneously. Baclofen blocks both the esophageal and the gastric distension-induced relaxation of the LES and inhibition of the crural diaphragm. The magnitude of response to baclofen was significantly larger for the crural diaphragm inhibition than for the LES relaxation. Baclofen, a GABAB receptor agonist, blocks the reflex inhibitory pathway to the LES and crural diaphragm. The reflex inhibitory pathway to the crural diaphragm is more sensitive to blockade by baclofen than the reflex LES inhibitory pathway. transient lower esophageal sphincter relaxation; gastroesophageal reflux; crural diaphragm; GABAB agonist TRANSIENT LOWER ESOPHAGEAL sphincter (LES) relaxation (TLESR) is the major mechanism of gastroesophageal reflux in normal subjects and patients with reflux disease (8, 23). Recent studies in animals and humans reveal that baclofen, a GABA B agonist, inhibits TLESR (3,11,13,28). Studies (10) documenting the blockade of TLESR by baclofen used the LES relaxation criteria to identify TLESR. During TLESR, along with LES, there is also inhibition of the other major component of the antireflux barrier, i.e., the crural diaphragm (21). Distension of the stomach in dogs induces TLESR, which is also associated with inhibition of the crural diaphragm (17). Simultaneous relaxation of the LES and inhibition of crural diaphragm also occurs during distension of the esophagus in cats (1). The effect of baclofen on the crural diaphragm inhibition during TLESR and esophageal distension is not known. The goals of our study were twofold: 1) to determine the effects of baclofen on the gastric distension-mediated LES relaxation and crural diaphragm inhibition, the two important components of the TLESR, and 2) to determine the effects of baclofen on the esophageal distension-mediated relaxation of the LES and inhibition of the crural diaphragm. MATERIALS AND METHODS Diaphragm electrodes implantation.These studies were conducted in five female adult cats, weighing between 3 and 3.7 kg. The protocol for the study was approved by The Animal Ethics Committee of the University of California, San Diego, and San Diego Veterans Affairs Hospital. Under general anesthesia induced by xylazine (1.5 m...

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Section: Discussionmentioning

confidence: 99%

Baclofen blocks LES relaxation and crural diaphragm inhibition by esophageal and gastric distension in cats

Liu

Pehlivanov

Mittal

2002

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…Tan & Miller (1986) (1986). Cherniack et al (1984) distended the mid-thoracic oesophagus of the dog using a 10 cm balloon and volumes of 50-200 ml of air. They found a graded inhibition of both costal and crural diaphragm EMG activities, a raised respiratory rate and increased activities of both internal and external intercostals.…”

Section: Discussionmentioning

confidence: 99%

“…Also the electrical activities of alae nasi, genioglossus and PCA were all increased by oesophageal distension. Cherniack et al (1984) speculated that activation of upper airway muscles would allow an intact animal (non-tracheostomized) to lower resistance to airflow and so maintain tidal volume in the face of reduced activity of the major respiratory pump muscles. In contrast, the present study suggests that at least the laryngeal portion of the upper airway does not dilate during oesophageal distension.…”

Section: Discussionmentioning

confidence: 99%

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The effects of oesophageal distension on diaphragm and laryngeal muscle activity in the anaesthetized cat

Jones¹,

McKeogh²,

Nolan³

et al. 1994

Experimental Physiology

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SUMMARYThe electromyographic (EMG) activities of diaphragm and laryngeal muscles were recorded during oesophageal distension in anaesthetized cats. The responses to distension of the thoracic oesophagus differed from those evoked by distension of the cervical oesophagus. The crural component of the diaphragm (CD) was inhibited by distension of the thoracic oesophagus; distension of the cervical oesophagus did not affect CD EMG. Thyroarytenoid (TA) muscle EMG increased markedly and consistently in response to distension of the cervical oesophagus. Distension of the thoracic oesophagus only produced statistically significant increases in TA EMG with high distending volume (10 ml) at the level of the gastro-oesophageal junction. The main abductor of the vocal cords, the posterior cricoarytenoid (PCA) was either unchanged or decreased by oesophageal distension. The electrical activities of left paratendinous diaphragm, left costal diaphragm, internal intercostal and external intercostal muscles remained unchanged. The entire pattern would appear to constitute a means to aid passage of a bolus into the stomach, and simultaneously guard the respiratory tract from reflux or aspiration.

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“…Recently it has been shown that the re spiratory related activity of the upper-air way dilating muscles and the cranial nerves which supply them are influenced by phasic vagal discharge [7]. With lung inflation, the amount of immediate inhibi tion is larger for all upper-airway dilating muscles than for the diaphragm [8,30].…”

Section: Introductionmentioning

confidence: 99%

Responses of Upper-Airway Dilating Muscles and Diaphragm Activity to End-Expiratory Pressure Loading in Anesthetized Dogs

Haxhiu¹,

Lunteren²,

Cherniack

1989

Respiration

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The steady-state responses of upper-airway dilating muscles and diaphragm activity to elevation of lung volume induced by positive end-expiratory pressure loading were studied in 9 pentobarbital-anesthetized dogs with vagus nerves intact. The early and late effects of 5 min of expiratory threshold loads upon upper airway dilating muscle activity (the alae nasi, the genioglossus and the posterior cricoarytenoid) were compared to their effects on diaphragm activity. During resting O₂ breathing, application of 5 and 10 cm H₂O of positive end-expiratory pressure produced no significant change in the peak electrical activity of the upper-airway dilating muscles and diaphragm (p > 0.05). No qualitative differences were found in the upper-airway dilating muscles and diaphragm responses to expiratory threshold loads when the animals breathed 3 or 7% CO₂ in O₂, compared to when they inspired 100% O₂. Furthermore, no differences were found in the electrical activity of the upper-airway dilating muscles and diaphragm at any given end-tidal CO₂ when unloaded responses were compared with loaded responses during progressive hypercapnia. However, positive end-expiratory pressure loading caused significant prolongation of expiratory duration, which gradually returned toward control levels when the loads were maintained. In animals who developed periodic breathing by increasing levels of anesthesia, positive end-expiratory pressure loading eliminated the periodicity and made the pattern of breathing regular. Based on these results, it can be concluded that under the conditions of these experiments, increases in lung volume produced by expiratory threshold loads do not reduce the activity of upper-airway dilating muscles. The maintenance of the electrical activity of the upper-airway dilating muscles might be caused by excitatory reflex mechanisms or central habituation.

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Responses of upper airway, intercostal and diaphragm muscle activity to stimulation of oesophageal afferents in dogs.

Cited by 40 publications

References 9 publications

Baclofen blocks LES relaxation and crural diaphragm inhibition by esophageal and gastric distension in cats

Baclofen blocks LES relaxation and crural diaphragm inhibition by esophageal and gastric distension in cats

The effects of oesophageal distension on diaphragm and laryngeal muscle activity in the anaesthetized cat

Responses of Upper-Airway Dilating Muscles and Diaphragm Activity to End-Expiratory Pressure Loading in Anesthetized Dogs

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