The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
A De Troyer - One of the best experts on this subject based on the ideXlab platform.
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Coupling between the ribs and the lung in dogs
The Journal of Physiology, 2002Co-Authors: A De TroyerAbstract:In contrast to the conventional theory, the external and Internal Intercostal Muscles show marked rostrocaudal gradients in their actions on the lung. We hypothesized that these gradients are the result of a non-uniform coupling between the ribs and the lung. Rib displacements (Xr) and the changes in airway opening pressure (Pa,o) were thus measured in anaesthetized, pancuronium-treated, supine dogs while loads were applied in the cranial direction to individual pairs of odd-numbered ribs and in the caudal direction to individual pairs of even-numbered ribs. During cranial loading, Xr induced by a given load increased gradually with increasing rib number. The decrease in Pa,o also increased from the third to the fifth rib pair but then decreased markedly to the eleventh pair. A similar pattern was observed during caudal loading, although Xr and ΔPa,o were smaller. These results were then combined to calculate the net Xr and the net ΔPa,o that a hypothetical Intercostal muscle lying parallel to the longitudinal body axis would produce in different interspaces. The net Xr was cranial in all interspaces. However, whereas the net ΔPa,o was negative in the cranial interspaces, it was positive in the caudal interspaces. These observations confirm that the coupling between the ribs and the lung varies from the top to the base of the ribcage. This coupling confers to both the external and the Internal Intercostal Muscles an inspiratory action on the lung in the cranial interspaces and an expiratory action in the caudal interspaces.
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Respiratory effects of the external and Internal Intercostal Muscles in humans.
The Journal of physiology, 2001Co-Authors: A Legrand, P A Gevenois, A De TroyerAbstract:The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. Recent studies in dogs, however, have shown that this notion is only approximate. In the present studies, the respiratory actions of the human external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the orientation of the muscle fibres relative to the ribs and the masses of the Muscles were first assessed in cadavers. Five healthy individuals were then placed in a computed tomographic scanner to determine the geometry of the ribs and their precise transformation during passive inflation to total lung capacity. The fractional changes in length of lines with the orientation of the muscle fibres were then computed to obtain the mechanical advantages of the Muscles. These values were finally multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the Muscles on the lung. The external Intercostal in the dorsal half of the second interspace was found to have a large inspiratory effect. However, this effect decreases rapidly in the caudal direction, in particular in the ventral portion of the ribcage. As a result, it is reversed into an expiratory effect in the ventral half of the sixth and eighth interspaces. The Internal Intercostals in the ventral half of the sixth and eighth interspaces have a large expiratory effect, but this effect decreases dorsally and cranially. The total pressure generated by all the external Intercostals during a maximum contraction would be -15 cmH2O, and that generated by all the Internal interosseous Intercostals would be +40 cmH2O. These pressure changes are substantially greater than those induced by the parasternal Intercostal and triangularis sterni Muscles, respectively.
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Response of the Canine Internal Intercostal Muscles to Chest Wall Vibration
American Journal of Respiratory and Critical Care Medicine, 2001Co-Authors: Dimitri Leduc, E. Brunko, A De TroyerAbstract:Although high-frequency mechanical vibration of the rib cage reduces dyspnea, its effects on the respiratory Muscles are largely unknown. We have previously shown that in anesthetized dogs, vibrating the rib cage during inspiration elicits a marked increase in the inspiratory electromyographic (EMG) activity recorded from the external Intercostal Muscles but does not affect tidal volume (Vt). In the present studies, we have tested the hypothesis that the maintenance of Vt results from the concomitant contraction of the Internal interosseous (expiratory) Intercostals. When the rib cage was vibrated (40 Hz) during hyperventilation-induced apnea, a prominent activity was recorded from the external Intercostals but no activity was recorded from the Internal Intercostals, including when the Muscles were lengthened by passive inflation. The Internal Intercostals remained also silent when vibration was applied during spontaneous inspiration, and the phasic expiratory EMG activity recorded from them was unaltered...
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles.
The Journal of physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:1. The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. 2. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the Muscles on the lung. 3. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. 4. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive.
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles
The Journal of Physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3·0 kg cm−2) to evaluate the potential effects of the Muscles on the lung. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive. Although it is now well established that the interchondral portion of the Internal Intercostal Muscles (the so-called parasternal Intercostals) elevates the ribs and inflates the lung when it contracts (De Troyer & Kelly, 1982; De Troyer et al. 1996), the actions of the external Intercostals and the interosseous portion of the Internal Intercostals remain uncertain. The current conventional view is based on the theory proposed 250 years ago by Hamberger (1749). According to this theory, the fibres of the external Intercostals slope obliquely caudad and ventrally from the rib above to the rib below, and so their lower insertion is further from the centre of rotation of the ribs (i.e. the costo-vertebral articulations) than their upper insertion. Consequently, when this muscle contracts with its force equal and opposite at both insertions, the torque acting on the lower rib, which tends to raise it, is greater than that acting on the upper rib, which tends to lower it. The net effect of the muscle, therefore, would be to raise the ribs and to inflate the lung. In contrast, the fibres of the Internal interosseous Intercostals slope obliquely caudad and dorsally from the rib above to the one below so that their lower insertion is closer to the centre of rotation of the ribs than the upper one. As a result, the net effect of their contraction would be to lower the ribs and to deflate the lung. This theory, however, has not been verified, and computations based on the orientation of the muscle fibres and on descriptions of rib displacement in dogs (Margulies et al. 1989) have recently suggested that the actions of the external and Internal Intercostal Muscles on the lung might vary between the dorsal and the ventral aspects of the rib cage as well as between the rostral and caudal interspaces (Wilson & De Troyer, 1993). In the present studies, we have examined the effects of the canine external and Internal interosseous Intercostals on the lung by using a standard theorem of mechanics, the Maxwell reciprocity theorem. When applied to the respiratory system (Wilson & De Troyer, 1992, 1993), this theorem predicts that the respiratory effect of a particular muscle (that is, the potential change in airway pressure - ΔPao - produced by the muscle contracting alone against a closed airway) is related to the mass (m) of the muscle, the maximal active muscle tension per unit cross-sectional area (σ), and the fractional change in muscle length (ΔL/L) per unit volume increase of the relaxed chest wall (ΔVL)Rel, such that: (1) For a machine, such as a lever, mechanical advantage is defined as the ratio of the force delivered at the load to the force applied at the handle. By analogy, the mechanical advantage of a respiratory muscle may therefore be defined as ΔPao/mσ and, according to eqn (1), could be evaluated by measuring (ΔL/(L ΔVL))Rel. In other words, a muscle that shortens during passive inflation would have an inspiratory mechanical advantage and would cause a fall in Pao when it contracts. Conversely, a muscle that lengthens during passive inflation would have an expiratory mechanical advantage and would cause a rise in Pao during contraction.
TA Wilson - One of the best experts on this subject based on the ideXlab platform.
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles.
The Journal of physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:1. The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. 2. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the Muscles on the lung. 3. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. 4. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive.
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles
The Journal of Physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3·0 kg cm−2) to evaluate the potential effects of the Muscles on the lung. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive. Although it is now well established that the interchondral portion of the Internal Intercostal Muscles (the so-called parasternal Intercostals) elevates the ribs and inflates the lung when it contracts (De Troyer & Kelly, 1982; De Troyer et al. 1996), the actions of the external Intercostals and the interosseous portion of the Internal Intercostals remain uncertain. The current conventional view is based on the theory proposed 250 years ago by Hamberger (1749). According to this theory, the fibres of the external Intercostals slope obliquely caudad and ventrally from the rib above to the rib below, and so their lower insertion is further from the centre of rotation of the ribs (i.e. the costo-vertebral articulations) than their upper insertion. Consequently, when this muscle contracts with its force equal and opposite at both insertions, the torque acting on the lower rib, which tends to raise it, is greater than that acting on the upper rib, which tends to lower it. The net effect of the muscle, therefore, would be to raise the ribs and to inflate the lung. In contrast, the fibres of the Internal interosseous Intercostals slope obliquely caudad and dorsally from the rib above to the one below so that their lower insertion is closer to the centre of rotation of the ribs than the upper one. As a result, the net effect of their contraction would be to lower the ribs and to deflate the lung. This theory, however, has not been verified, and computations based on the orientation of the muscle fibres and on descriptions of rib displacement in dogs (Margulies et al. 1989) have recently suggested that the actions of the external and Internal Intercostal Muscles on the lung might vary between the dorsal and the ventral aspects of the rib cage as well as between the rostral and caudal interspaces (Wilson & De Troyer, 1993). In the present studies, we have examined the effects of the canine external and Internal interosseous Intercostals on the lung by using a standard theorem of mechanics, the Maxwell reciprocity theorem. When applied to the respiratory system (Wilson & De Troyer, 1992, 1993), this theorem predicts that the respiratory effect of a particular muscle (that is, the potential change in airway pressure - ΔPao - produced by the muscle contracting alone against a closed airway) is related to the mass (m) of the muscle, the maximal active muscle tension per unit cross-sectional area (σ), and the fractional change in muscle length (ΔL/L) per unit volume increase of the relaxed chest wall (ΔVL)Rel, such that: (1) For a machine, such as a lever, mechanical advantage is defined as the ratio of the force delivered at the load to the force applied at the handle. By analogy, the mechanical advantage of a respiratory muscle may therefore be defined as ΔPao/mσ and, according to eqn (1), could be evaluated by measuring (ΔL/(L ΔVL))Rel. In other words, a muscle that shortens during passive inflation would have an inspiratory mechanical advantage and would cause a fall in Pao when it contracts. Conversely, a muscle that lengthens during passive inflation would have an expiratory mechanical advantage and would cause a rise in Pao during contraction.
A Legrand - One of the best experts on this subject based on the ideXlab platform.
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Respiratory effects of the external and Internal Intercostal Muscles in humans.
The Journal of physiology, 2001Co-Authors: A Legrand, P A Gevenois, A De TroyerAbstract:The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. Recent studies in dogs, however, have shown that this notion is only approximate. In the present studies, the respiratory actions of the human external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the orientation of the muscle fibres relative to the ribs and the masses of the Muscles were first assessed in cadavers. Five healthy individuals were then placed in a computed tomographic scanner to determine the geometry of the ribs and their precise transformation during passive inflation to total lung capacity. The fractional changes in length of lines with the orientation of the muscle fibres were then computed to obtain the mechanical advantages of the Muscles. These values were finally multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the Muscles on the lung. The external Intercostal in the dorsal half of the second interspace was found to have a large inspiratory effect. However, this effect decreases rapidly in the caudal direction, in particular in the ventral portion of the ribcage. As a result, it is reversed into an expiratory effect in the ventral half of the sixth and eighth interspaces. The Internal Intercostals in the ventral half of the sixth and eighth interspaces have a large expiratory effect, but this effect decreases dorsally and cranially. The total pressure generated by all the external Intercostals during a maximum contraction would be -15 cmH2O, and that generated by all the Internal interosseous Intercostals would be +40 cmH2O. These pressure changes are substantially greater than those induced by the parasternal Intercostal and triangularis sterni Muscles, respectively.
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles.
The Journal of physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:1. The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. 2. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3.0 kg cm-2) to evaluate the potential effects of the Muscles on the lung. 3. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. 4. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive.
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Respiratory mechanical advantage of the canine external and Internal Intercostal Muscles
The Journal of Physiology, 1999Co-Authors: A De Troyer, A Legrand, TA WilsonAbstract:The current conventional view of Intercostal muscle actions is based on the theory of Hamberger (1749) and maintains that as a result of the orientation of the muscle fibres, the external Intercostals have an inspiratory action on the lung and the Internal interosseous Intercostals have an expiratory action. This notion, however, remains unproved. In the present studies, the respiratory actions of the canine external and Internal Intercostal Muscles were evaluated by applying the Maxwell reciprocity theorem. Thus the effects of passive inflation on the changes in length of the Muscles throughout the rib cage were assessed, and the distributions of muscle mass were determined. The fractional changes in muscle length during inflation were then multiplied by muscle mass and maximum active stress (3·0 kg cm−2) to evaluate the potential effects of the Muscles on the lung. The external Intercostals in the dorsal third of the rostral interspaces were found to have a large inspiratory effect. However, this effect decreases rapidly both toward the costochondral junctions and toward the base of the rib cage. As a result, it is reversed to an expiratory effect in the most caudal interspaces. The Internal Intercostals in the caudal interspaces have a large expiratory effect, but this effect decreases ventrally and rostrally, such that it is reversed to an inspiratory effect in the most rostral interspaces. These observations indicate that the canine external and Internal Intercostal Muscles do not have distinct inspiratory and expiratory actions as conventionally thought. Therefore, their effects on the lung during breathing will be determined by the topographic distribution of neural drive. Although it is now well established that the interchondral portion of the Internal Intercostal Muscles (the so-called parasternal Intercostals) elevates the ribs and inflates the lung when it contracts (De Troyer & Kelly, 1982; De Troyer et al. 1996), the actions of the external Intercostals and the interosseous portion of the Internal Intercostals remain uncertain. The current conventional view is based on the theory proposed 250 years ago by Hamberger (1749). According to this theory, the fibres of the external Intercostals slope obliquely caudad and ventrally from the rib above to the rib below, and so their lower insertion is further from the centre of rotation of the ribs (i.e. the costo-vertebral articulations) than their upper insertion. Consequently, when this muscle contracts with its force equal and opposite at both insertions, the torque acting on the lower rib, which tends to raise it, is greater than that acting on the upper rib, which tends to lower it. The net effect of the muscle, therefore, would be to raise the ribs and to inflate the lung. In contrast, the fibres of the Internal interosseous Intercostals slope obliquely caudad and dorsally from the rib above to the one below so that their lower insertion is closer to the centre of rotation of the ribs than the upper one. As a result, the net effect of their contraction would be to lower the ribs and to deflate the lung. This theory, however, has not been verified, and computations based on the orientation of the muscle fibres and on descriptions of rib displacement in dogs (Margulies et al. 1989) have recently suggested that the actions of the external and Internal Intercostal Muscles on the lung might vary between the dorsal and the ventral aspects of the rib cage as well as between the rostral and caudal interspaces (Wilson & De Troyer, 1993). In the present studies, we have examined the effects of the canine external and Internal interosseous Intercostals on the lung by using a standard theorem of mechanics, the Maxwell reciprocity theorem. When applied to the respiratory system (Wilson & De Troyer, 1992, 1993), this theorem predicts that the respiratory effect of a particular muscle (that is, the potential change in airway pressure - ΔPao - produced by the muscle contracting alone against a closed airway) is related to the mass (m) of the muscle, the maximal active muscle tension per unit cross-sectional area (σ), and the fractional change in muscle length (ΔL/L) per unit volume increase of the relaxed chest wall (ΔVL)Rel, such that: (1) For a machine, such as a lever, mechanical advantage is defined as the ratio of the force delivered at the load to the force applied at the handle. By analogy, the mechanical advantage of a respiratory muscle may therefore be defined as ΔPao/mσ and, according to eqn (1), could be evaluated by measuring (ΔL/(L ΔVL))Rel. In other words, a muscle that shortens during passive inflation would have an inspiratory mechanical advantage and would cause a fall in Pao when it contracts. Conversely, a muscle that lengthens during passive inflation would have an expiratory mechanical advantage and would cause a rise in Pao during contraction.
J. R. Romaniuk - One of the best experts on this subject based on the ideXlab platform.
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Pattern of expiratory muscle activation during lower thoracic spinal cord stimulation
2016Co-Authors: A. F. Dimarco, J. R. Romaniuk, Gerald S. Supinski, K. E. KowalskiAbstract:G. Supinski. Pattern of expiratory muscle activation during lower thoracic spinal cord stimulation. J. Appl. Physiol. 86(6): 1881–1889, 1999.—Large positive airway pressures (Paws) can be generated by lower thoracic spinal cord stimulation (SCS), which may be a useful method of restoring cough in spinal cord-injured patients. Optimal electrode placement, however, requires an assessment of the pattern of current spread during SCS. Studies were performed in anesthetized dogs to assess the pattern of expiratory muscle recruitment during SCS applied at different spinal cord levels. A multicon-tact stimulating electrode was positioned over the surface of the lower thoracic and upper lumbar spinal cord. Recording electromyographic electrodes were placed at several locations in the abdominal and Internal Intercostal Muscles. SCS was applied at each lead, in separate trials, with single shocks o
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Mechanical action of the Internal Intercostal Muscles in dogs
Journal of Applied Physiology, 1993Co-Authors: Anthony F. Dimarco, Gerald S. Supinski, B. Simhai, J. R. RomaniukAbstract:The pattern of electrical activation and muscle length changes of the Internal Intercostal (II) Muscles (9th or 10th interspace) of the lower rib cage were evaluated in supine anesthetized dogs. Studies were performed during resting breathing and expiratory threshold loading. Results were compared with simultaneous measurements of the better-studied triangularis sterni muscle (4th interspace). In general, both Muscles lengthened with passive inflation and shortened with passive deflation. During resting breathing, both the II and TS Muscles were electrically active and shortened below resting length, 7.7 +/- 1.6% (SE) and 5.3 +/- 1.7%, respectively. With the addition of positive end-expiratory pressure, the degree of electrical activation and muscle shortening increased progressively for both Muscles, although to a somewhat greater extent for II Muscles. Isolated denervation of the II Muscles eliminated their shortening during resting breathing and often resulted in muscle lengthening, indicating that II muscle shortening was secondary to its own activation. Expiration was associated with lateral inward movement of the lower rib cage below its relaxation position. This motion was not significantly affected by abdominal muscle section but was markedly reduced by bilateral II denervation (7th-11th spaces). Our results indicate that the II Muscles of the lower rib cage 1) are electrically active and shorten below resting length during resting breathing, 2) respond to positive end-expiratory pressure by increasing their level of activation and degree of shortening, and 3) are primarily responsible for inward lateral motion of the lower rib cage below its relaxation position during expiration.
Vyskocil F - One of the best experts on this subject based on the ideXlab platform.
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Different sensitivity of miniature endplate currents in rat external and Internal Intercostal Muscles to the acetylcholinesterase inhibitor C-547 as compared with diaphragm and extensor digitorum longus
2020Co-Authors: Petrov K., Bukharaeva E., Nikolsky E., Vyskocil FAbstract:Derivative of 6-methyluracil, selective cholinesterase inhibitor C-547 potentiates miniature endplate currents (MEPCs) in rat external Intercostal Muscles (external ICM) more effectively than in Internal Intercostal Muscles (Internal ICM). Effect of the C-547 on Intercostal Muscles was compared with those on extensor digitorum longus (EDL) and diaphragm Muscles. Half-effective concentrations for τ of MEPC decay arranged in increasing order were as follows: EDL, locomotor muscle, most sensitive = 1.3 nM, external ICM, inspiration muscle = 6.8 nM, diaphragm, main inspiration muscle = 28 nM, Internal ICM, expiration muscle = 71 nM. External ICM might therefore be inhibited, similarly as the limb Muscles, by nanomolar concentrations of the drug and do not participate in inspiration in the presence of the C-547. Moreover, Internal ICM inhibition can hinder the expiration during exercise-induced fast breathing of C-547- treated experimental animals. © 2009 by the Institute of Physiology, Czech Academy of Sciences
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Different sensitivity of miniature endplate currents in rat external and Internal Intercostal Muscles to the acetylcholinesterase inhibitor C-547 as compared with diaphragm and extensor digitorum longus.
Physiological research, 2009Co-Authors: Konstantin A. Petrov, I. V. Kovyazina, Vladimir V. Zobov, Ellya Bukharaeva, Evgeny E. Nikolsky, Vyskocil FAbstract:Summary Derivative of 6-methyluracil, selective cholinesterase inhibitor C547 potentiates miniature endplate currents (MEPCs) in rat external Intercostal Muscles (external ICM) more effectively than in Internal Intercostal Muscles (Internal ICM). Effect of the C-547 on Intercostal Muscles was compared with those on extensor digitorum longus (EDL) and diaphragm Muscles. Half-effective concentrations for τ of MEPC decay arranged in increasing order were as follows: EDL, locomotor muscle, most sensitive = 1.3 nM, external ICM, inspiration muscle = 6.8 nM, diaphragm, main inspiration muscle = 28 nM, Internal ICM, expiration muscle = 71 nM. External ICM might therefore be inhibited, similarly as the limb Muscles, by nanomolar concentrations of the drug and do not participate in inspiration in the presence of the C-547. Moreover, Internal ICM inhibition can hinder the expiration during exercise-induced fast breathing of C-547- treated experimental animals.