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PubMed1992

Respiration in vitro: II. Electrical stimulation.

The present report describes electrical-stimulation-induced activity recorded from intercostal muscles in the neonatal rat rib-attached, in vitro brain stem-spinal cord preparation. The muscle bursts induced by electrical stimulation included a short-latency twitch contraction and a long-latency modulated contraction similar to that observed during spontaneous respiratory-like activity. Multilevel recordings showed a cephalocaudal order of recruitment of intercostal muscles similar to that observed during spontaneous activity. The optimal parameters of stimulation were 2-msec pulses delivered at 0.1-0.2 Hz. Trains of pulses also were effective. These movements could be induced following stimulation of various sites within each segment of the spinal cord, with the lowest threshold sites located in the ventrolateral funiculus and intermediate gray. Stimulation of every cervical segment was effective in inducing respiratory-like activity, with the lowest-threshold segments being C1, C2, and C5. These results suggest that low-frequency, long-duration pulses applied directly to the spinal cord can induce respiratory-like activity similar to that observed during spontaneous activity in the neonatal rat, rib-attached in vitro brain stem-spinal cord preparation. The ability to elicit a coordinated respiratory pattern even after a high spinal transection suggests that such stimulation may be effective in inducing respiratory-like activity in the absence of descending brain stem connections.

Animals↗

PubMed1975

The effect of some local anaesthetics upon the electrical and mechanical activity of respiratory muscles in cats during pentobarbital anaesthesia.

No thorough investigation has been made of the effect of small intravenous doses of local anaesthetics upon respiration, although those agents are extensively used for clinical purposes. This prompted a study of the effects of rapid intravenous injections of 2 and 4 mg/kg lidocaine, 3 and 7 mg/kg mepivacaine and 0.4 and 0.8 mg/kg bupivacaine upon the electrical and mechanical activity of the respiratory muscles. Studies were also made of the effects of 3 mg/kg lidocaine when gas mixtures of different carbon dioxide and oxygen content were bein g breathed. The experimental animals were 43 cats, anaesthetized with 35 mg/kg pentobarbital intraperitoneally. Recordings were made of the number of impulses and the maximal impulse frquency from the external intercostal muscles, the diaphragm and the phrenic nerve, together with the tidal volume, minute ventilation, breathing frequency, duration of inspiration, and, during occluded breaths, the maximal pressure and the pressure impulses generated by the inspiratory muscles. It was found that all of the agents investigated had a clear effect upon respiration. The most marked changes became apparent during the first few minutes following the injections, and the effects lasted 10-20 minutes, as judged from changes observed in the recorded parameters. No differences could be seen in the effects of lidocaine and mepivacaine upon respiration, except as regards the effect upon inspiratory time. However, both of these agents differed from bupivacaine in the r effects. Lidocaine and mepivacaine depressed the activity of the external intercostal muscles, whereas the changes recorded from the diaphragm were much less marked...

Anesthetics, Local↗

PubMed1992

Respiration in vitro: I. Spontaneous activity.

The present report describes respiratory-like activity recorded from intercostal muscles in the neonatal rat in vitro brain stem-spinal cord, rib-attached preparation. In this preparation from 1- to 4-day-old rats, spontaneous rhythmic and synchronized upward movements of the rib cage coincided with the recorded muscle activity. Spontaneous respiratory-like activity showed a frequency in the range of 0.05-0.2 Hz, with single-, double-, and mixed-burst patterns. Spontaneous activity declined over time, but increased in frequency as temperature increased. Multilevel recordings showed a cephalocaudal order of bursting of intercostal muscles. Brain stem transections at the prepontine level did not affect spontaneous frequency, whereas premedullary transections resulted in an increase in spontaneous respiratory frequency. High spinal transections eliminated spontaneous respiratory-like activity. These results suggest that there is a well-organized pontomedullary pattern generator for respiratory-like activity in this preparation, which can be modulated by temperature. The characteristics of these electromyographic (EMG) recordings allow comparison with previous in vitro studies of respiratory-like activity using nerve activity and in vivo studies using EMG activity. These results provide basic information on the spontaneous activity of this preparation as a prelude to the study of the effects of electrical stimulation of the spinal cord to induce respiratory-like activity, as described in the companion article.

Animals↗

PubMed1983

[Significance of the corpus callosum in the paired activity of the respiratory center].

The asymmetrical reactions of respiratory neurons of the right and left halves of the respiratory center and varied changes in bioelectrical activity of external intercostal muscles on both sides of the chest were discovered in experiments on anesthetized cats in response to successive electrical stimulation of the symmetrical cortical areas of the right and left cerebral hemispheres before and after callosotomy. It was demonstrated that callosotomy increased on both sides of the respiratory center the quantity of neurons responsive to ipsilateral cortical stimulation and determined the character of the asymmetrical reactions of right and left respiratory neurons and intercostal muscles. On the basis of the data obtained it is concluded that the corpus callosum contributes to the functional integration of both halves of the respiratory center.

Animals↗

PubMed2002

MCP-1 and MIP-2 response in Trichinella spiralis infected mice treated with 4-deoxypyridoxine (4-DPD).

Chemokines are involved in a number of pathophysiological conditions, such as inflammatory processes and are divided in two major subfamilies, C-X-C and C-C chemokines. The C-C chemokines are monocyte chemotactic protein 1-2-3-4-5, while C-X-C chemokines include MIP-2, IL-8, etc. We studied the levels of MCP-1 and MIP-2 in diaphragmatic and intercostal muscle tissue and serum in Trichinella spiralis infected mice treated and not treated with 4-deoxypyridoxine, a potent Vit. B6 antagonist which inhibits humoral and cellular immune response. MCP-1 and MIP-2 were measured in homogenized tissue and serum and determined by a specific ELISA. Here we found the levels of MCP-1 and MIP-2 in diaphragmatic and intercostal muscle tissue of T. spiralis infected mice were significantly increased after 10 days and peaked on day 20 post-infection; however, the levels of MIP-2 in mice treated with 4-DPD was lower than that of untreated mice at day 20. MCP-1 also peaked at days 20 and 40. Animals treated with 4-DPD also inhibited the production of MCP-1, compared with untreated animals. The maximum inhibition was at day 40. These inhibitory effects on MIP-2 and MCP-1 were also repeated in the serum determinations, but were not significant. This study demonstrates that MIP-2 and MCP-1 are stimulated in serum and tissue of T. spiralis infected mice and 4-DPD-treated animals significantly inhibited them.

Animals↗

PubMed1998

Dermomyotomal origin of the ribs as revealed by extirpation and transplantation experiments in chick and quail embryos.

To elucidate role of the dermomyotome in the formation of the axial skeleton, we performed extirpation and transplantation experiments on the dermomyotomes in chick and quail embryos. When the thoracic dermomyotomes of chick embryos were removed, the intercostal muscles and the distal ribs were deficient, while the proximal ribs were more or less normal. Quail tissues including the dermomyotome, the ectoderm and the medial edge of lateral plate, were transplanted to replace chick dermomyotomes. In these chimeras, the ribs, which would be deficient without the back-transplantation, were recovered. The cells of the recovered part of the ribs as well as the intercostal muscles were derived from the quail transplants. These findings suggest that the distal rib originated from the dermomyotomes and not the sclerotome as previously believed. To localize the origin of the distal rib further, we removed restricted regions of the dermomyotomes along the mediolateral and the rostrocaudal axis. The more lateral the part of the dermomyotomes that we removed, the more distal the part of the ribs affected. On the contrary, when the rostral and caudal edges of the dermomyotomes were removed, only the vertebral ribs showed extensive deficiencies while removal of the middle part between the edges caused less deficiency. The sternal ribs were not deficient in either case, but were extensively affected when the entire lateral edge of dermomyotomes was included in the region removed. We conclude that the lateral edges of the dermomyotomes are the primordia of the sternal ribs, and the rostral and/or caudal edges of the medial part of dermomyotomes are the primordia of the distal part and not of the proximal part of the vertebral ribs.

Animals↗

PubMed1999

Abnormal regulation of muscle contraction in horses with recurrent exertional rhabdomyolysis.

OBJECTIVE: To determine whether abnormal regulation of muscle contraction similar to that associated with malignant hyperthermia (MH) was evident in intact external intercostal muscle cells from Thoroughbreds with recurrent exertional rhabdomyolysis (RER). ANIMALS: 5 adult Thoroughbred horses with RER and 7 clinically normal adult Thoroughbred or mixed-breed horses. PROCEDURES: Twitch time course variables and contracture responses to various concentrations of potassium, caffeine, and halothane were measured in small bundles of intact external intercostal muscle cells from clinically normal horses and horses with RER. RESULTS: Threshold for significant contracture induced by potassium depolarization was lower for RER-affected muscles, compared with normal muscles, although the relationship between potassium concentration and membrane potential were not different. Thresholds for contracture induced by caffeine and halothane were also lower for RER-affected muscles, compared with normal muscles. Lower thresholds for caffeine- and halothane-induced contractures, as well as depolarization-elicited contractures, in RER-affected muscles suggest a defect in myoplasmic calcium regulation. CONCLUSIONS AND CLINICAL RELEVANCE: Regulation of muscle contraction is abnormal in Thoroughbreds with RER. The specific defect may be attributable to abnormal intracellular calcium regulation. Knowledge of the specific defect involved in RER may lead to improved prevention and treatment of RER-affected horses.

Anesthetics, Inhalation↗

PubMed1994

Evaluation of intercostal pacing to provide artificial ventilation in quadriplegics.

The purpose of this study was to assess the utility of intercostal muscle pacing by spinal cord stimulation (SCS) to provide artificial ventilation in ventilator-dependent quadriplegic patients. Five ventilator-dependent quadriplegics with phrenic nerve injury (and therefore not candidates for phrenic nerve pacing) were studied. During an initial surgical procedure, a quadripolar epidural disc electrode was positioned on the ventral portion of the upper thoracic spinal cord via a hemilaminectomy and subsequently connected to a radio-frequency receiver implanted subcutaneously over the anterior rib cage. In four of the five patients, initial SCS stimulation resulted in inspired volumes between 150 and 240 ml. Stimulation resulted in no effect in one patient, due to probable cystic degeneration of the thoracic spinal cord. Reconditioning of the intercostal muscles caused substantial increases in inspired volume in three of four patients of 670 to 850 ml. In one patient, reconditioning resulted in a much smaller increase (to 470 ml). The maximum duration that ventilation could be sustained by low-frequency (13 Hz) intercostal pacing ranged between 20 min and 2 3/4 h. Our findings indicate that intercostal pacing via SCS does not result in sufficient inspired volume production to support ventilation for prolonged periods. However, this modality may be a useful adjunct to enhance tidal volume in patients with suboptimal inspired volume by phrenic nerve pacing.

Chronic Disease↗

PubMed1996

Respiratory muscle response to flail chest.

We have previously shown that flail chest in the dog causes an inspiratory inward displacement of the ribs and an increased inspiratory activity in the external intercostal muscles, and we have speculated that this increased activity is due to an increased spindle afferent activity. The present studies were designed to test this hypothesis. Twenty-nine supine anesthetized dogs were studied, and flail was produced surgically by fracturing ventrally and dorsally two to four contiguous ribs on the right side of the chest. Although flail elicited an increased inspiratory activity in the external intercostal and levator costae muscles in the disconnected segment of the rib cage, it did not alter the inspiratory activity in the diaphragm and parasternal intercostals. Expiratory activity in the triangularis sterni, internal intercostals, and transversus abdominis remained unchanged also, as did the inspiratory activity in the external intercostals on the left side of the chest. After flail, the normal inspiratory shortening of the external intercostal muscles in the disconnected segment was also reversed into an inspiratory muscle lengthening. However, when the fractured ribs were connected to the adjacent ribs so that the external intercostals were prevented from lengthening during inspiration, external intercostal and levator costae inspiratory activity was unaltered. These observations support the hypothesis that the increased external intercostal muscle activity seen in flail chest results primarily from an increased activation of the muscle spindles.

Animals↗

PubMed1990

Development and survival of thoracic motoneurons and hindlimb musculature following transplantation of the thoracic neural tube to the lumbar region in the chick embryo: functional aspects.

Following heterotopic transplantation of the thoracic neural tube to the lumbar region on embryonic day (E) 2, the transplanted cord differentiates normally and establishes neuroanatomical connections with the host central nervous system and hindlimb muscles. Beginning on about E12, however, the neuromuscular system begins to undergo regressive changes resulting in motoneuron degeneration and muscle atrophy (O'Brien and Oppenheim, 1990). In the present paper, we have examined the development of neuromuscular function in thoracic transplant embryos from E6 to the time of hatching on E20-21. The onset of hindlimb movements and reflexes occurred at the same time (E6-E8) in both control and thoracic transplant embryos. Further, both the nature (pattern) and frequency of these movements appeared normal in the thoracic transplants up to E10-E12, after which there was a gradual and marked reduction in the frequency, and an alteration in the pattern, of both spontaneous and reflex-evoked hindlimb movements. After E16 normal movements were virtually absent in many of the thoracic transplant cases. By contrast, movements of the head, trunk and wings were normal in these embryos throughout the observation period. Hindlimbs innervated partly by the thoracic transplant and partly by remaining host lumbar cord did not exhibit the regressive changes in function after E10 that occurred in hindlimbs innervated exclusively by the thoracic transplant. EMG recordings from specific hindlimb muscles innervated solely by thoracic motoneurons demonstrated that the activation pattern of both flexors and extensors was similar to the repetitive pattern observed in normal thoracically innervated intercostal muscles (i.e., extensor-like). Muscles did not show distinguishable EMG burst patterns with inhibitory periods as do control lumbar innervated muscles. We conclude that the development of the pattern generating circuitry in the transplanted thoracic cord was similar to normal thoracic cord and thus appeared to be uninfluenced by having contacted the foreign hindlimb muscle targets early in development. Activity blockade with curare from E6 to E14 suppressed the loss of motoneurons that occurs in the thoracic transplant after E10. Thus, the abnormal thoracic-like activation pattern of thoracically innervated hindlimbs may be a critical signal in the initiation of the neuromuscular regression that occurs after E10 in these preparations. Finally, although the innervation and formation of neuromuscular endplates in thoracic transplants appeared normal up to E12, by E14 both the intramuscular nerves and the endplates exhibited signs of degeneration and regression. Thoracic motoneurons are initially able to innervate and functionally activate hindlimb muscles in a manner similar to that of thoracically innervated intercostal muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1976

Postural hypoxemia in quadriplegic patients.

Quadriplegic patients frequently undergo unusual positional changes, including head-down tilt. To determine if hypoxemia develops in this position and whether it is related to the duration of quadriplegia, five patients were studied within 1 year of injury (group A) and five after 1 year from injury (group B). Arterial blood gases were obtained in the seated and 45-degree head-down position. Group A patients had a decrease in arterial partial pressure of oxygen in the head-down position (p less than 0.025), while group B patients did not (p greater than 0.4). This study demonstrated that quadriplegic patients have positional hypoxemia early in their course. This probably results from relative hypoventilation of the upper lung fields caused by flaccid paralysis of the intercostal muscles. The positional hypoxemia disappears with time, presumably because of the change from flaccid to spastic paralysis of the intercostal muscles.

Humans↗

PubMed1992

Anatomic basis of tracheobronchial reconstruction by intercostal flap.

A feasibility study was carried out to standardise the use of the intercostal muscle flap (ICF) for reconstruction of the posterior wall of the trachea and bronchi. The program consisted of two stages. Morphologically, in anatomic specimens, intercostal muscle flaps were dissected that could be used whatever the morphotype of the subject. Ten human cadavers were dissected after a right thoracotomy in the 6th right intercostal space, providing flaps 12 to 18 cm long and 1.5 to 3 cm wide. Experimentally, studies were made on 7 dogs of the functional and anatomopathologic aspects of the reconstruction at the 20th postoperative day. The results showed impermeability and rapid healing at endoscopy on the 10th postoperative day in every case as well as regeneration of ciliated epithelium in 6 of the 7 cases. The ICF may therefore be considered for losses of tracheobronchial substance, whether accidental, spontaneous (fistulae) or deliberate (surgery for malignant or benign lesions).

Animals↗

PubMed1985

Muscle cell electrical hyperpolarization and reduced exercise hyperkalemia in physically conditioned dogs.

Contracting muscle cells release K ions into their surrounding interstitial fluid, and some of these ions, in turn, enter venous plasma. Thereby, intense or exhaustive exercise may result in hyperkalemia and potentially dangerous cardiotoxicity. Training not only reduces hyperkalemia produced by exercise but in addition, highly conditioned, long-distance runners may show resting hypokalemia that is not caused by K deficiency. To examine the factors underlying these changes, dogs were studied before and after 6 wk of training induced by running on the treadmill. Resting serum [K] fell from 4.2 +/- 0.2 to 3.9 +/- 0.3 meq/liter (P less than 0.001), muscle intracellular [K] rose from 139 +/- 7 to 148 +/- 14 meq/liter (P less than 0.001), and directly measured muscle cell membrane potential (Em) in vivo rose from -92 +/- 5 to -103 +/- 5 mV (P less than 0.001). Before training, resting Em of isolated intercostal muscle in vitro was -87 +/- 5 mV, and after incubation in 10(-4) M ouabain, Em fell to -78 +/- 5 mV. After training, resting Em of intercostal muscle rose to -95 +/- 4, but fell to -62 +/- 4 mV during incubation in 10(-4) M ouabain. The measured value for the Em was not completely explained by the increased ratio of intracellular to extracellular [K] or by the potassium diffusion potential. Skeletal muscle sarcolemmal Na,K-ATPase activity (microM inorganic phosphate mg-1 protein h-1) increased from 0.189 +/- 0.028 to 0.500 +/- 0.076 (P less than 0.05) after training, whereas activities of Mg2+ -dependent ATPase and 5'nucleotidase did not change. In untrained dogs, exercise to the point of exhaustion elevated serum [K] from 4.4 +/- 0.5 to 6.0 +/- 1.0 meq/liter (P less than 0.05). In trained dogs, exhaustive exercise was associated with elevation of serum [K] from 3.8 +/- 0.3 to 4.2 +/- 0.4 (NS). The different response of serum [K] to exercise after training was not explainable by blood pH. Basal insulin levels rose from 7.0 +/- 0.7 microU/ml in the untrained dogs to 9.9 +/- 1.0 microU/ml (P less than 0.05) after training. Although insulin might have played a role in the acquired electrical hyperpolarization, the reduced exercise-produced hyperkalemia after training was not reversed by blockade of insulin release with somatostatin. Although the fundamental mechanisms underlying the cellular hyperpolarization were not resolved, our observations suggest that increased Na-K exchange across the sarcolemmal membrane, the increase of Na,K-ATPase activity and possibly increased electrogenicity of the sodium pump may all play a role in the changes induced by training.

Animals↗

PubMed2004

[Chest wall epithelioid sarcoma].

Two relatively rare cases of epithelioid sarcoma located in the chest wall are reported herein. The first was a tumor, 3.8 x 5.5 x 2.4 cm in size, originating in the left erector spinae muscle of a man 64 years of age. He experienced local recurrence 3 times even after wide resections, and he died of systemic metastasis 22 months after the initial surgery. The second was a tumor, 2.2 x 2.0 x 1.5 cm in size, originating in the left seventh intercostal muscle of a woman 24 years of age. A metastatic tumor occurred in the same muscle, and wide resection including the seventh and eighth intercostal muscles was performed. There has been no recurrence for 1.5 years since surgery. Metastasis of chest wall epithelioid sarcoma in the muscle in which the primary lesion resides should be considered, even if the primary lesion is small.

Adult↗

PubMed1992

Severe neonatal nemaline myopathy--histological and histochemical studies of respiratory muscles.

The histological and histochemical findings in the respiratory muscles of a patient with severe neonatal nemaline myopathy are described. The patient suffered from frequent pneumonia associated with vomiting due to gastroesophageal reflux and died at 3 months from respiratory failure. The diaphragm was moderately involved and the intercostal muscles mildly involved. Core/targetoid structures were observed in the diaphragm and intercostal muscles.

Comorbidity↗

PubMed1983

Congenital myasthenia gravis in 13 smooth fox terriers.

In 13 Smooth Fox Terriers with a congenital form of myasthenia gravis, clinical signs included intermittent, progressive muscle weakness that became more pronounced with exercise; muscle wasting; megaesophagus; and aspiration pneumonia. Neurologic abnormalities were apparent only during periods of weakness and included inability to retract the fore- and hindlimbs from painful stimuli. A decrement of the compound muscle action potential was evident during repetitive supramaximal nerve stimulation. Intravenous injection of a short-acting cholinesterase inhibitor evoked immediate improvement of clinical and electromyographic signs. Intracellular microelectrode studies of a biopsied external intercostal muscle revealed reduced amplitude of miniature end-plate potentials, as occurs in acquired myasthenia gravis. However, in contrast to acquired myasthenia gravis, antibodies directed against acetylcholine receptors were not demonstrable in serum and were not bound to acetylcholine receptors in muscle. Despite lack of complexing with immunoglobulin, the amount of acetylcholine receptor protein in biopsied external intercostal muscles from 9 affected pups was less than 25% of the amount in 5 unaffected littermates. The latter finding accounted for the reduction in amplitude of miniature end-plate potential and the failure of neuromuscular transmission. Treatment with a long-acting cholinesterase inhibitor in 6 cases resulted in temporary improvement in muscle strength.

Animals↗

PubMed1986

Regional lung perfusion and ventilation with radioisotopes in cervical cord-injured patients.

In general, cervical cord-injured patients present with restrictive pulmonary dysfunction resulting from paralysis of the intercostal muscles. Vital capacity frequently decreases below 50% of that in normal subjects, and their respiratory pattern frequently includes paradoxical movement in which the intercostal spaces sink and the abdomen distends at inspiration. Ventilation scintigraphy using Xe-133 and pulmonary perfusion scintigraphy using Tc-99m macroaggregated albumin (MAA) were performed on nine cervical cord-injured patients and four normal subjects to investigate regional lung functions in the cervical cord-injured patients. Pulmonary perfusion scintigraphy, in which measurement was made in the supine position, revealed no differences between the patients and the normal subjects. The inhomogeneous ventilation/perfusion distribution was presumed to have resulted from change in regional intrapleural pressure due to paradoxical movement of the thoracic cage. Washing and washout times were prolonged by paralysis of the intercostal muscles. These phenomena were particularly apparent in the upper and middle lung regions where compensating action by movement of the diaphragm is small.

Adult↗

PubMed1980

Tonic inspiratory muscle activity as a cause of hyperinflation in histamine-induced asthma.

We studied the change in tonic activity of the inspiratory muscles during acute hyperinflation. Hyperinflation was provoked in two asthmatic and three normal subjects by progressively doubling doses of histamine. Changes in lung volume were determined with magnetometers and with a body plethysmograph. Intercostal muscle activity was recorded with surface electrodes and diaphragmatic activity with esophageal electrodes. Tonic activity was defined as electrical activity in the electromyogram present at end expiration. After histamine the maximal observed increase in plethysmographic thoracic gas volume in the five subjects was 29.8 +/- 6.4% of control (mean +/- SE). Hyperinflation was accompanied by a significant increase in tonic activity of the intercostal muscles (P < 0.01) and the diaphragm (P < 0.01). There was a significant correlation between the increase in thoracic gas volume and the increase in tonic intercostal (r = 0.82, P = 0.003) and diaphragmatic (r = 0.89, P = 0.003) activity. We conclude that histamine-induced hyperinflation is accompanied by persistent inspiratory muscle activity throughout expiration.

Adult↗