Structural basis for decreased compressibility of constricted tracheae and bronchi.

Olsen, C. Robert; Stevens, A; Pride, N. B.; Staub, Norman C.

doi:10.1152/jappl.1967.23.1.35

Cited by 55 publications

(35 citation statements)

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“…The difference between inside and outside narrowing cannot be accounted for through simple occupation of the lumen by the airway wall. VAN HAYEK [21] described submucosal separation in human bronchial sections, and independent movement of different cartilage pieces in response to deforming pressure has been noted in the cat bronchus [22]. The present findings were made by the simultaneous imaging on the inside and the outside of the bronchial segment.…”

Section: Discussionmentioning

confidence: 55%

Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig

Mitchell¹,

Sparrow²

1994

Eur Respir J

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V Vi id de eo o--i im ma ag gi in ng g o of f l lu um me en n n na ar rr ro ow wi in ng g; ; m mu us sc cl le e s sh ho or rt te en ni in ng g a an nd d f fl lo ow w r re es sp po on ns si iv ve en ne es ss s i in n i is so ol la at te ed d b br ro on nc ch hi ia al l s se eg gm me en nt ts s o of f t th he e p pi ig g ABSTRACT: The amount of smooth muscle shortening required to cause narrowing of the bronchial lumen and to significantly alter airflow in an airway has not been measured directly. Accordingly, in this study, the lumens of isolated fluid-filled bronchial segments from pigs were directly visualized using a fibreoptic endoscope and video-recording. The extent of lumen narrowing was related to smooth muscle contraction, determined morphometrically, and to bronchial lumen flow. Narrowing was produced by electrical field stimulation ( The use of direct video-imaging has shown that functional airway closure is associated with an approximate halving of the lumen diameter but less shortening of the smooth muscle. The greater movement of the luminal than adventitial margins suggests that the smooth muscle and mucosa move independently of the cartilaginous part of the bronchial wall during airway narrowing.

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Section: Discussionmentioning

confidence: 55%

Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig

Mitchell¹,

Sparrow²

1994

Eur Respir J

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“…This region can expand during muscle constriction in vitro, suggesting that it may also be compressible [1,31]. In vitro, fluid appears able to enter the wall of isolated bronchi across their adventitial surface (unpublished obervations) whether this can occur in the lung in vivo, is questionable.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous forces acting on the airway wall, including transmural pressure and smooth muscle contraction, may distend or narrow conducting airways [1][2][3][4]. Compliant airways are more susceptible both to distension and compression by these forces.…”

mentioning

confidence: 99%

Bronchial compliance and wall structure during development of the immature human and pig lung

McFawn¹,

Mitchell²

1997

Eur Respir J

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Maturational changes in the specific compliance could potentially contribute to the development or clinical presentation of respiratory diseases in infants and children. Changes in the specific compliance during development and its structural basis have been well characterized, but changes in bronchial compliance and the mechanisms involved have received little attention.Semistatic pressure-volume curves were generated for isolated bronchial segments from late-term foetal, immature and adult pigs. A small number of bronchi from human infants were also studied. The amount of cartilage in the bronchial wall of pigs of different ages was measured histologically, and morphometric changes in the wall of inflated bronchi were investigated.The specific compliance of bronchi approximately halved from 1 to 4 weeks of age. No change in specific compliance was observed either between 4 week old and adult pigs, or between late-term foetal and 1 week old pigs. Changes in the total wall and cartilage areas did not correlate with changes in specific compliance. Inflation to 20 cmH 2 O transmural pressure reduced the total wall area of bronchi from 1 week old pigs.Significant changes in bronchial distensibility occur during the early postnatal period. These changes in specific compliance are not caused by an increase in the amount of cartilage. The increase in luminal volume during inflation of bronchial segments occurs, partially, by compression of the airway wall against the cartilage layer.

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“…Tracheal smooth muscle is known to resist distension (9). At negative transmural pressures (as in forced expiration), invagination of the pars membrana is resisted and the tracheal smooth muscle tone opposes collapse of the adult airway (10). On the other hand, bronchial smooth muscle contraction results in bronchial narrowing but effective prevention of collapse (10).…”

Section: E T H O D Smentioning

confidence: 99%

The Role of Tracheal Smooth Muscle Contraction on Neonatal Tracheal Mechanics

1986

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ABSTRACT'. The ability of tracheal smooth muscle tone to modulate the mechanical properties of neonatal airways was evaluated in six newborn lambs. Tracheal pressurevolume relationships, isovolumic compliance, hysteresis, and the relaxation time constant of the smooth muscle were evaluated as a function of incremental cholinergic stimulation. Tracheal active tensions were also determined at the graded levels of cholinergic stimulation. Data show that a maximal cholinergic stimulation resulted in a mean developed active tension value of 14.3 2 2.13 SEM x 10" dyneslcm. The resultant 55% decrease in tracheal compliance was linearly correlated to the increase in active tension linergic stimulation was utilized to alter smooth muscle tone and its effect on tracheal elastic and viscoelastic behavior were determined. The relationship between tracheal compliance, hysteresis, and relaxation time constant of the smooth muscle were evaluated as a function of the change in tracheal smooth muscle tension. M E T H O D SAnimal preparation. Six full-term newborn lambs, 1 to 3 days postpartum, were anesthetized (30 mg/kg intraperitoneal pentabarbital) and secured in the supine position. The ventral surface of the neck was dissected to reveal the upper trachea, and the exposed tracheal area proximal to the thoracic cage was transected and cannulated to allow spontaneous ventilation. Vascular integrity was maintained and subsequently verified by cholinergic stimulation. The left jugular vein was cannulated, and electrocardiographic leads were attached to the lamb.Proximal tracheal segments of 2.8 cm in length were measured and isolated. A plug was inserted in the most caudal end of the bypassed segment (Fig. 1). The lambs were then intubated with an endotracheal tube secured in place with ligatures at the cricoid cartilage. A rigid frame was affixed externally to the bypassed segments to maintain constant length during the experimental procedures.Tracheal smooth muscle tone plays an important and significant role in the conductance and the dimensions of the adult tracheobronchial tree (1). Coburn and Palombini (2) have demonstrated that graded increases in the active tension of the trachealis muscle results in a proportional decrease in the adult canine tracheal compliance. Other effects of smooth muscle tension on adult tracheal mechanics have been documented with respect to its viscoelastic properties (3), regulation (4), and structure-function (5). It is well accepted that neonatal airways are compliant structures (6, 7). Although these in vitro studies have provided valuable information concerning the passive properties of the airways, the effect of smooth muscle tone on the functional behavior of neonatal airways is not known. The relationship between smooth muscle contraction and mechanical function of the immature trachea has not been evaluated, hence it is unclear whether airway rigidity and function can be controlled at early stages of development.The purpose of this study was to evaluate the role of tracheal smooth muscl...

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Structural basis for decreased compressibility of constricted tracheae and bronchi.

Cited by 55 publications

References 0 publications

Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig

Video-imaging of lumen narrowing; muscle shortening and flow responsiveness in isolated bronchial segments of the pig

Bronchial compliance and wall structure during development of the immature human and pig lung

The Role of Tracheal Smooth Muscle Contraction on Neonatal Tracheal Mechanics

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