SEARCH · PubMed Health

Results for “INTERCOSTAL MUSCLES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed1988

Medullary neurons mediating the inhibition of inspiration by intercostal muscle tendon organs?

Studies were conducted to test the hypothesis that nonrespiratory-modulated units are last-order interneurons mediating the effects of intercostal muscle tendon organs on medullary inspiratory neuron activity. Vagotomized, anesthetized, or decerebrate cats were used. Results show the following. 1) Afferents from different receptor types (i.e., intercostal tendon organs and chest wall cutaneous receptors) that inhibit medullary inspiratory neuron activities evoke the same units. 2) Gastrocnemius muscle group I afferent fibers evoke some of the same units as intercostal afferents but do not alter respiratory activity. 3) The "pneumotaxic center" and laryngeal nerve afferents, which inhibit medullary inspiratory activity, evoke different medullary units than intercostal afferents. 4) Evoked units are not active in spontaneously breathing cats. Additional results suggest that a few respiratory neurons near the retrofacial nucleus may be involved in the mediation of the inspiratory inhibitory effects of intercostal tendon organs. These results do not establish the mechanism by which intercostal muscle tendon organs reduces medullary inspiratory activity.

Afferent Pathways↗

PubMed1992

Na+ current densities and voltage dependence in human intercostal muscle fibres.

1. Voltage-clamp Na+ currents (INa) were studied in human intercostal muscle fibres using the loose-patch-clamp technique. 2. The fibres could be divided into two groups based upon the properties of INa. The two groups of fibres were called type 1 and type 2. 3. Both type 1 and type 2 fibres demonstrated fast and slow inactivation of INa. 4. Type 1 fibres had lower INa on the endplate border and extrajunctional membrane than type 2 fibres and required larger membrane depolarizations to inactivate Na+ channels by fast or slow inactivation of INa. 5. Type 2 fibres had a higher ratio of INa at the endplate border compared to extrajunctional membrane than Type 1 fibres. 6. Measurement of membrane capacitance suggested that the increase in INa at the endplate border was due to increased Na+ channel density. 7. Histochemical staining of some fibres suggested that type 1 fibres were slow twitch and type 2 fibres were fast twitch. 8. Differences in the properties of Na+ channels between fast- and slow-twitch fibres may contribute to the ability of fast-twitch fibres to operate at high firing frequencies and slow-twitch fibres to be tonically active.

Electric Stimulation↗

PubMed1966

Sodium, potassium, and chloride fluxes in intercostal muscle from normal goats and goats with hereditary myotonia.

IN ISOLATED BUNDLES OF EXTERNAL INTERCOSTAL MUSCLE FROM NORMAL GOATS AND GOATS WITH HEREDITARY MYOTONIA THE FOLLOWING WERE DETERMINED: concentrations and unidirectional fluxes of Na(+), K(+), and Cl(-), extracellular volume, water content, fiber geometry, and core-conductor constants. No significant difference between the two groups of preparations was found with respect to distribution of fiber size, intracellular concentrations of Na(+) or Cl(-), fiber water, resting membrane potential, or overshoot of action potential. The intracellular Cl(-) concentration in both groups of preparations was 4 to 7 times that expected if Cl(-) were distributed passively between intracellular and extracellular water. The membrane permeability to K (P(K)) calculated from efflux data was (a) at 38 degrees C, 0.365 x 10(-6) cm sec(-1) for normal and 0.492 x 10(-6) for myotonic muscle, and (b) at 25 degrees C, 0.219 x 10(-6) for normal and 0.199 x 10(-6) for myotonic muscle. From Cl(-) washout curves of normal muscle usually only three exponential functions could be extracted, but in every experiment with myotonic muscle there was an additional, intermediate component. From these data PP(cl) could be calculated; it was 0.413 x 10(-6) cm sec(-1) for myotonic fibers and was 0.815 x 10(-6) cm sec(-1) for normal fibers. The resting membrane resistance of myotonic fibers was 4 to 6 times greater than that of normal fibers.

Animals↗

PubMed1996

Rostrocaudal gradient of electrical activation in the parasternal intercostal muscles of the dog.

1. Because the inspiratory mechanical advantage of the canine parasternal intercostal muscles is greatest in the third interspace and decreases gradually in the caudal direction, the electromyograms of these muscles in interspaces 3, 5 and 7 have been recorded in anaesthetized, spontaneously breathing dogs. Each activity was expressed as a percentage of the activity measured during tetanic, supramaximal stimulation of the internal intercostal nerve (maximal activity). 2. Parasternal inspiratory activity during resting, room air breathing was invariably greater in the third than in the fifth interspace (62.0 +/- 6.0 vs. 41.3 +/- 4.6% of maximal activity; P < 0.001) and smallest in the seventh interspace (22.8 +/- 2.7% of maximal activity; P < 0.001). This distribution of activity persisted during hyperoxic hypercapnia and during breathing against increased inspiratory airflow resistance. 3. This rostrocaudal distribution of activity also persisted after complete paralysis of the diaphragm as well as after deafferentation of the ribcage. 4. Studies of the distribution of the muscle fibre types indicated that the parasternal intercostals in all interspaces had a higher proportion of slow-twitch oxidative (SO; type I) fibres than fast-twitch oxidative-glycolytic (FOG; type II a) fibres. 5. Thus the topographic distribution of parasternal inspiratory activity along the rostrocaudal axis of the ribcage is precisely matched with the topographic distribution of mechanical advantage. This extraordinarily effective pattern of activation probably results from the unequal distribution of central inputs throughout the parasternal motoneurone pool.

Animals↗

PubMed1971

Cable parameters, sodium, potassium, chloride, and water content, and potassium efflux in isolated external intercostal muscle of normal volunteers and patients with myotonia congenita.

In isolated fiber bundles of external intercostal muscle from each of 13 normal volunteers and each of 6 patients with myotonia congenita, some or all of the following were measured: concentrations of Na(+), K(+), and Cl(-), extracellular volume, water content, K(+) efflux, fiber size, fiber cable parameters, and fiber resting potentials. Muscle from patients with myotonia congenita differed significantly (0.001 <P< 0.025) with respect to the following mean values (myotonia congenita vs. normal): the membrane resistance was greater (5729 vs. 2619 omega.cm(2)), the internal resistivity was less (75.0 vs. 123.2 omega.cm), the water content was less (788.2 vs. 808.2 ml/kg wet weight), and the mean resting potential was greater (68 vs. 61 mv).NO SIGNIFICANT DIFFERENCES WERE FOUND WITH RESPECT TO THE FOLLOWING VARIABLES: K(+) content (73.5 vs. 66.7 mEq/kg wet weight) and the calculated intracellular K(+) concentration (215 vs. 191 mEq/liter fiber water), fiber capacitance (5.90 vs. 5.15 muf/cm(2)), Na(+) content (97.7 vs. 94.1 mEq/kg wet weight), Cl(-) content (79.0 vs. 74.7 mEq/kg wet weight), mannitol extracellular volume (45.1 vs. 46.6 cc/100 g wet weight), and K(+) efflux (23.2 vs. 21.5 moles x 10(-12) cm(-2).sec(-1)). These abnormalities of skeletal muscle in human myotonia congenita are like those of skeletal muscle in goats with hereditary myotonia. We tentatively conclude that a decreased Cl(-) permeability accounts for some of the abnormal electrical properties of skeletal muscle in myotonia congenita.

Action Potentials↗

PubMed1982

Cholinesterase activity of the motor endplate in rat intercostal muscle.

Cholinesterase activity was localized solely in the motor endplate of the membrane in rate intercostal muscle. The diameter of rat motor endplates in the gradient dimension was 31.9 micrometers. The cholinesterase activity per unit protein of the soluble fraction of rat muscle membrane was 35.6% higher than the original membrane. From studies with specific substrates and cholinesterase inhibitors, the cholinesterase activity of rat muscle membrane and its soluble fraction consists of more than 90% acetylcholinesterase and less than 10% pseudocholinesterase.

Animals↗

PubMed1994

The comparative effects of elastase-induced emphysema on costal and crural diaphragm and parasternal intercostal muscle contractility.

Chronically, hyperinflated human subjects with chronic obstructive pulmonary disease and animals with experimentally induced emphysema generate greater than expected levels of transdiaphragmatic pressure at high lung volume because of adaptive changes in the length-tension relationship of the costal diaphragm. The ability to lower intrathoracic pressure during inspiration depends on the mechanical action of all the inspiratory muscles acting in concert. However, the effect of chronic hyperinflation on the mechanical action of inspiratory muscles other than the costal diaphragm remains unknown. This study compares the effect of chronic hyperinflation in the form of elastase-induced emphysema on the contractile properties of the three major inspiratory muscles of the hamster (i.e., the costal and crural diaphragm and parasternal intercostals). Muscles were studied in vitro 6 months after emphysema was induced by intratracheal injection of elastase. Saline-injected animals served as controls. TLC in the elastase-injected hamsters was significantly greater than in controls (12.5 +/- 0.8 ml versus 9.0 +/- 0.3 ml, p < 0.002). Maximal tetanic tension, time to peak tension, maximal velocity of shortening, and the force-velocity relationship differed among the three muscles but for any given muscle were similar in control and emphysematous animals. In contrast, the fiber length optimal for tension generation (Lo) not only differed across muscles but was significantly shorter in the costal diaphragm of emphysematous animals compared with control animals. However, Lo of the parasternal intercostal and crural diaphragm was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed2001

Response of the canine internal intercostal muscles to chest wall vibration.

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 when vibration was applied during expiration. Thus, the internal interosseous intercostals in dogs are much less sensitive to vibration than the external intercostals, and they do not interfere with the action of these latter during rib cage vibration. This lack of sensitivity might be the result of a reflex inhibition of the muscle spindle afferents by afferents from external intercostal muscle spindles.

Animals↗

PubMed1993

Change in recruitment order of motor units in human parasternal intercostal muscles with sleep state.

Recruitment order of individual motor units in the early part of inspiration in parasternal intercostal muscles was observed in normal human subjects during wakefulness and non-rapid-eye-movement sleep. Electromyograms from bipolar fine wire intramuscular electrodes were recorded while the subjects lay supine in a sleep laboratory, and sleep stage was determined by polysomnography. From wakefulness to sleep there were numerous examples of shifts in order of recruitment among the low threshold units of early inspiration. There were corresponding shifts in the order of derecruitment of these units. Analysis of frequency of firing of units also suggested that the levels of excitatory input to one unit of a pair could be altered relative to the level of input of the other one. The data imply that there are at least minor differences in distribution of excitatory inputs from various sources among motoneurons of this muscle pool.

Electromyography↗

PubMed1986

Effects of carotid chemoreceptor stimulating and depressing agents on internal intercostal muscle activity in the rabbit.

The effects of carotid chemoreceptor stimulating and depressing agents on internal intercostal muscle activity (IIMA) were studied before and after surgical denervation of the carotid sinus nerve (CSN) in the rabbit. An intracarotid injection of 30 micrograms of sodium cyanide (NaCN) during inspiration caused an increase in both IIMA and respiratory rate (RR). In contrast, intracarotid administration of 10 micrograms of dopamine (DA) during inspiration resulted in a decrease in both IIMA and RR. The NaCN- and DA-induced characteristic responses in IIMA were abolished by the section of the CSN. The results indicate that the excitatory and inhibitory responses of IIMA to intracarotid injections of NaCN and DA are mainly mediated through carotid chemoreflexes.

Animals↗

PubMed1998

Morphology of single primary spindle afferents of the intercostal muscles in the cat.

A reconstruction was made of the trajectory of primary spindle afferents from the intercostal muscles in the spinal cord of the cat. Intraaxonal recordings were performed from the primary spindle afferents that were identified by their response to lung inflation and stimulus threshold to activate the action potentials. The afferents were stained by using intraaxonal injection of horseradish peroxidase (HRP). Results were obtained mainly from internal intercostal Ia fibers, which entered the spinal cord and bifurcated into ascending and descending branches. The ascending branches could be traced up to 10.7 mm, and the descending branches could be traced up to 7.3 mm. The ascending branches extended to the next segment. Collaterals ranging from one to six were given off from these branches. The distances between adjacent collaterals ranged from 0.9 mm to 4.7 mm. Each collateral had similar morphological characteristics. The collaterals entered the dorsal horn and ran toward lamina IX through the medial half of the gray matter. Fine branches and boutons were given off in laminae V, VII, VIII, and IX. The aggregations of these branches were found in lamina VII, mainly in the region of Clarke's column and in the ventral and ventrolateral regions thereof and in lamina IX, mainly in the nucleus lateromedialis. Most terminals did not contact the somata of target neurons in all laminae in which terminals were found. However, a few terminals were found to contact large neurons in lamina IX. In addition to these aggregates, there were some terminals scattered throughout the ventral horn. Thus, it was concluded that single intercostal Ia afferents project to the region of Clarke's column, to the intercostal motor nucleus, and to the intermediate regions.

Afferent Pathways↗

PubMedDate not supplied

Membrane currents in human intercostal muscle at varied extracellular potassium.

Hyperpolarizing and depolarizing square steps were imposed on the membrane potential of excised human intercostal muscle fibers by means of a 3-microelectrode voltage clamp. The steady-state amplitudes of the membrane currents inducing such steps were investigated as a function of the membrane potential, while the muscle was bathed in solutions varying in potassium content (Ke = 1, 3.5, 7, 20, and 60 mM). At all potassium concentrations, the membrane acted as a rectifier, both in the inward- and outward-going directions. Inward currents were much reduced when Ke was lowered from 3.5 to 1 mM, and were increased when Ke was raised beyond 3.5 mM. The delayed outward current was reduced when Ke was increased from 3.5 mM to 7 mM and higher potassium concentration. The results were qualitatively similar to those reported for rat skeletal muscle.

Cell Membrane↗

PubMed2005

[Recording expulsive forces during childbirth using intercostal muscle electromyogram: a pilot study].

OBJECTIVE: The expulsive forces of childbirth can be included among the many potential risk factors implicated in the subsequent development of perineal disorders. The objective of this study was to devise a non-invasive way to measure abdominal pushing that would accurately represent the expulsive forces during childbirth. PATIENTS AND METHODS: By means of intravesical and intrauterine manometry, and electromyography (EMG) of intercostal muscles, we quantified these forces in 21 women during vaginal delivery. RESULTS: A mixed Ancova model showed the integral of intravesical pressure to be significantly associated (P<0.001) with the integral of intercostal muscle electrical activity during the first 6 uterine contractions during the phase of fetal expulsion. DISCUSSION AND CONCLUSION: Electromyography is a non-invasive measurement that can replace intravesical determinations to quantify these forces as it reflects the real intra-abdominal pressure.

Adult↗

PubMed1994

Effects of pentobarbital anesthesia on intercostal muscle activation and shortening.

Although pentobarbital (PB) is a commonly used anesthetic in animal studies examining respiratory motor control, there are virtually no studies that have examined the differential effects of deepening anesthesia on the activation of the various intercostal muscles. In dogs, anesthetized initially with 25 mg/kg of PB, the effects of additional doses of PB (20 mg) provided every 15 min on intercostal electromyogram (EMG) were monitored. In each animal, peak external intercostal (EI) and levator costae (LC) activation progressively decreased with additional doses of PB and were eventually abolished, at which point peak parasternal (PA) EMG had increased to 127 +/- 13% (SE) of control values; peak diaphragm EMG was unaffected. The reductions in EI activation were associated with progressive reductions in EI muscle shortening that, in turn, were associated with progressive reductions in lateral rib cage expansion. PA shortening was not significantly affected. Similar results were obtained in animals breathing supplemental oxygen. These results indicate that 1) activation of EI and LC compared with PA have divergent responses, with EI and LC decreasing and PA increasing; 2) the fall in EI activation results in decrements in EI shortening and lateral rib cage motion; and 3) anesthetic depth is an important variable that must be controlled in studies assessing intercostal muscle activation.

Anesthesia↗

PubMed1998

[Fiber morphometry of the external intercostal muscle. Comparison of dominant and nondominant sides in patients with severe COPD].

The general morphometric characteristics of the external intercostal muscle (EIM) of patients with chronic respiratory disease have been well described. Because this muscle is highly accessible, it can provide an ideal model for longitudinal studies using consecutive biopsies of both sides. Whether or not the EIM fiber phenotype is homogeneous on dominant (D) and non dominant (ND) sides is unknown, however. To evaluate possible structural differences in right and left EIM in patients with COPD, eight patients (63 +/- 7 years of age) were enrolled. Lung function, respiratory muscle power, general muscle power and nutritional state were evaluated. Biopsies of the fifth EIM were taken from both sides. Specimens were processed in parallel manner to determine conventional morphometry (hematoxylin-eosin staining), including minimum diameter (Dm) and fiber area (Ar) in cross sections. Fibers were typed by ATPase (at pH 4.2, 4.6 and 9.4) and NADH-TR staining. Nutrition was normal in all patients. All patients had severe COPD (FEV1 27 +/- 7% of reference, limits 13 to 38% of reference) with air entrapment (RV 163 +/- 36% of reference, limits 181 to 276% of reference). None of the patients showed respiratory insufficiency at rest (PaO2 72 +/- 7 mmHg). Peripheral musculoskeletal power measured by manual dynamometer showed no significant right-left differences: D 29 +/- 2 and ND 28 +/- 3 dynes. Morphometric study of 16 muscle specimens showed no significant differences between fiber size on D and ND sides. DmD was 47 +/- 10 microns and ArD, was 2,595 +/- 1,249 microns2. DmD was 49 +/- 9 microns and ArD was 2,636 +/- 953 microns2. Likewise, no significant differences were found between D and ND fiber types: type ID 51 +/- 4% and type IID 49 +/- 5% versus type IND 52 +/- 4% and type IIND 48 +/- 4%. EIM on N and ND sides is homogeneous at the fifth intercostal space. This finding, along with the scarcely invasive nature of the technique for collecting specimens leads us to suggest that longitudinal studies might be performed on the structural effects of various pharmacological or physical treatments followed by COPD patients

Aged↗

PubMed1987

Effects of temporal trachea-occlusion at the end of expiration on internal intercostal muscle activity in the rabbit.

The effects of temporal trachea-occlusion at the end of expiration on internal intercostal muscle activity (IIMA) and diaphragmatic activity (DMA) were studied in the vagi-intact rabbit. This tracheal occlusion caused a marked prolongation of inspiration time due to a diminution of the vagally mediated inspiratory inhibition but the significant change in the next IIMA was not observed after releasing tracheal occlusion. In addition, the effects of temporal trachea-occlusion on pulmonary stretch receptor activity (PSRA) and DMA were also studied in the unilaterally vagotomized rabbit. The procedures remarkably inhibited the respiratory modulation of PSRA from inspiration to expiration. These results indicate that the change of PSRA in response to temporal trachea-occlusion does not significantly affect the next IIMA.

Airway Obstruction↗

PubMed1999

Postinspiratory activity of the parasternal and external intercostal muscles in awake canines.

Previous studies have shown in awake dogs that activity in the crural diaphragm, but not in the costal diaphragm, usually persists after the end of inspiratory airflow. It has been suggested that this difference in postinspiratory activity results from greater muscle spindle content in the crural diaphragm. To evaluate the relationship between muscle spindles and postinspiratory activity, we have studied the pattern of activation of the parasternal and external intercostal muscles in the second to fourth interspaces in eight chronically implanted animals. Recordings were made on 2 or 3 successive days with the animals breathing quietly in the lateral decubitus position. The two muscles discharged in phase with inspiration, but parasternal intercostal activity usually terminated with the cessation of inspiratory flow, whereas external intercostal activity persisted for 24.7 +/- 12.3% of inspiratory time (P < 0.05). Forelimb elevation in six animals did not affect postinspiratory activity in the parasternal but prolonged postinspiratory activity in the external intercostal to 45.4 +/- 16.3% of inspiratory time (P < 0.05); in two animals, activity was still present at the onset of the next inspiratory burst. These observations support the concept that muscle spindles are an important determinant of postinspiratory activity. The absence of such activity in the parasternal intercostals and costal diaphragm also suggests that the mechanical impact of postinspiratory activity on the respiratory system is smaller than conventionally thought.

Animals↗

PubMed1986

An analysis of action of intercostal muscles in human upper rib cage.

The actions of the intercostal and paraspinal muscles in stabilizing the human upper rib cage have been analyzed using a geometrically realistic mathematical model of the first six ribs, vertebrae, and associated musculature. The model suggests roles of the deep layers of erector spinae in stabilizing the vertebral column so that it can support the loads placed upon it by the ribs under physiological load. If we assume that the tension exerted by an intercostal muscle is proportional to its local thickness, the model predicts that the observed distribution of intercostal thickness is close to that which minimizes the stresses in ribs when the model is subjected to peak physiological load. The observed shape of the ribs are optimal to withstand the calculated pattern of loading along their length. These calculations raise the hypothesis that the arrangement of intercostal musculature and rib geometry result in an optimally light rib cage, which is capable of withstanding the loads placed upon it. The analysis of the mechanics of the entire model indicates that the geometrical simplifications made in Hamberger's model are not valid when applied to the rib cage.

Biomechanical Phenomena↗