Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MUSCLES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 739 records · Page 41Linked to original sources
PubMed1999

The role of diet components, gastrointestinal factors, and muscle innervation on activation of protein synthesis in skeletal muscles following oral refeeding.

The aim of this study was to quantify the effect of oral refeeding on the synthesis of soluble and contractile proteins in skeletal muscles, and to evaluate to what extent diet components (carbohydrate, fat, amino acids), hormones (insulin, IGF-I, GIP), Ca2+ flux, polyamine synthesis, cyclooxygenase activity, and muscle innervation are related to activation of protein synthesis at the translational level following oral refeeding. Adult, weight-stable, non-growing mice (C57B1) were used in starvation/refeeding experiments with oral chow. Growing rats (150 g) were used in parenteral refeeding experiments. Protein synthesis was measured in vivo in mixed muscles (phenylalanine flooding), in phasic EDL muscles (in vitro), and in cultured L-6 muscle cells. Overnight starvation reduced synthesis of soluble proteins by 37 +/- 8% (from 0.242 +/- 0.025 to 0.151 +/- 0.009 microgram-1.mg-1) and contractile proteins by 55 +/- 6% (from 0.148 +/- 0.018 to 0.068 microgram-1.mg-1) (P < 0.01). Soluble proteins with a basic net charge were more sensitive to nutrition compared to neutral and acidic proteins. Somatostatin treatment before refeeding attenuated muscle protein synthesis by 15% (P < 0.02). Mechanical stimulation of the gastrointestinal tract (bulk feeding) did not activate protein synthesis in muscles, while i.v. or i.p. provision of nutrients did. Oral refeeding normalized rates of protein synthesis within 3 h (P < 0.01), independently of intact muscle innervation, Ca2+ flux, polyamine synthesis, and cyclooxygenase activity in the skeletal muscles, while it was dependent on a complete substrate composition of the oral diet. Our results support the hypothesis that amino acids, probably in concerted action with locally produced tissue IGF-I, stimulate protein synthesis in skeletal muscles during refeeding.

Amino Acids↗
PubMed1972

Early biochemical consequences of denervation in fast and slow skeletal muscles and their relationship to neural control over muscle differentiation.

1. One week after denervation several biochemical characteristics of the fast extensor digitorum longus and slow soleus muscles from adult rats were investigated and compared with the characteristics of the corresponding unoperated contralateral muscles. 2. After these short periods of denervation-induced atrophy, the isolated myosins showed unchanged ATPase (adenosine triphosphatase) activities, but there was the expected difference between fast and slow muscle. 3. The specific activities of several soluble enzymes and their characteristic patterns were found to be only slightly modified in both the extensor and soleus muscles after denervation, as were most of the activities measured in the isolated mitochondria. 4. The most significant modifications were in the isolated sarcoplasmic reticulum, and appeared to be specific to either slow or fast muscle. 5. Denervation of slow muscle led to a marked increase of Ca(2+)-transport rates, and of the specific activity of the Mg(2+)-activated K(+)-modulated Ca(2+)-stimulated ATPase, together with changes in the polyacrylamide-electrophoretic profiles of the microsomal membrane protein. Transformation of these several properties of slow muscle sarcoplasmic reticulum to those of fast muscle sarcoplasmic reticulum was further substantiated by electron-microscopic analysis after negative staining. Control experiments with tenotomized soleus muscle gave negative results. 6. The isolated sarcoplasmic reticulum from fast muscle showed a slight diminution of ATPase-linked Ca(2+)-transport activity and a selective increase of rotenone-insensitive NADH-cytochrome c reductase activity, in addition to a greater emphasis on slow-type electrophoretic components of the structural membrane protein. 7. The significance of these results in relation to specific differentiating influences from motor nerves is discussed.

Adenosine Triphosphatases↗
PubMed2004

Re-examination of the possible role of Golgi tendon organ and muscle spindle reflexes in proprioceptive neuromuscular facilitation muscle stretching.

Literature concerning the theoretical role of spinal reflex circuits and their sensorimotor signals in proprioceptive neuromuscular facilitation (PNF) muscle stretching techniques was examined. Reviewed data do not support the assertion commonly made in PNF literature that contraction of a stretched muscle prior to further stretch, or contraction of opposing muscles during muscle stretch, produces relaxation of the stretched muscle. Further, following contraction of a stretched muscle, inhibition of the stretch reflex response lasts only 1 s. Studies examined suggested that decreases in the response amplitude of the Hoffmann and muscle stretch reflexes following a contraction of a stretched muscle are not due to the activation of Golgi tendon organs, as commonly purported, but instead may be due to presynaptic inhibition of the muscle spindle sensory signal. The current view on the complex manner by which the spinal cord processes proprioceptive signals was discussed. The ability of acute PNF stretching procedures to often produce a joint range of motion greater than that observed with static stretching must be explained by mechanisms other than the spinal processing of proprioceptive information. Studies reviewed indicate that changes in the ability to tolerate stretch and/or the viscoelastic properties of the stretched muscle, induced by PNF procedures, are possible mechanisms.

Elasticity↗
PubMed2001

Effects of purified recombinant neural and muscle agrin on skeletal muscle fibers in vivo.

Aggregation of acetylcholine receptors (AChRs) in muscle fibers by nerve-derived agrin plays a key role in the formation of neuromuscular junctions. So far, the effects of agrin on muscle fibers have been studied in culture systems, transgenic animals, and in animals injected with agrin--cDNA constructs. We have applied purified recombinant chick neural and muscle agrin to rat soleus muscle in vivo and obtained the following results. Both neural and muscle agrin bind uniformly to the surface of innervated and denervated muscle fibers along their entire length. Neural agrin causes a dose-dependent appearance of AChR aggregates, which persist > or = 7 wk after a single application. Muscle agrin does not cluster AChRs and at 10 times the concentration of neural agrin does not reduce binding or AChR-aggregating activity of neural agrin. Electrical muscle activity affects the stability of agrin binding and the number, size, and spatial distribution of the neural agrin--induced AChR aggregates. Injected agrin is recovered from the muscles together with laminin and both proteins coimmunoprecipitate, indicating that agrin binds to laminin in vivo. Thus, the present approach provides a novel, simple, and efficient method for studying the effects of agrin on muscle under controlled conditions in vivo.

Agrin↗
PubMed2006

Muscle fibre recruitment can respond to the mechanics of the muscle contraction.

This study investigates the motor unit recruitment patterns between and within muscles of the triceps surae during cycling on a stationary ergometer at a range of pedal speeds and resistances. Muscle activity was measured from the soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) using surface electromyography (EMG) and quantified using wavelet and principal component analysis. Muscle fascicle strain rates were quantified using ultrasonography, and the muscle-tendon unit lengths were calculated from the segmental kinematics. The EMG intensities showed that the body uses the SOL relatively more for the higher-force, lower-velocity contractions than the MG and LG. The EMG spectra showed a shift to higher frequencies at faster muscle fascicle strain rates for MG: these shifts were independent of the level of muscle activity, the locomotor load and the muscle fascicle strain. These results indicated that a selective recruitment of the faster motor units occurred within the MG muscle in response to the increasing muscle fascicle strain rates. This preferential recruitment of the faster fibres for the faster tasks indicates that in some circumstances motor unit recruitment during locomotion can match the contractile properties of the muscle fibres to the mechanical demands of the contraction.

Adult↗
PubMed1974

Effect of denervation on the adaptation of sarcomere number and muscle extensibility to the functional length of the muscle.

1. The effects of denervation on the response of the cat soleus muscle to immobilization at different lengths by plaster casts has been investigated for a period of 4 weeks.2. The passive length-tension properties of the denervated immobilized muscles were not significantly different from those of non-denervated muscles. Muscles immobilized in the shortened position showed a marked decrease in extensibility whether they were denervated or not. In all the other cases the length-tension curves were not significantly differetn from those of normal muscles.3. The denervated soleus muscle immobilized in the lengthened position was found to produce 25% more sarcomeres in series, whilst those immobilized in the shortened position lost 35%. This adaptation was essentially the same as in muscles that had been immobilized but not denervated.4. Denervation was found to have no effect on the recovery of muscles that had been subjected to 4 weeks immobilization in the shortened position. In these muscles the sarcomere increased back to the normal level within 4 weeks after removal of the plaster cast.5. The adjustment of sarcomere number to the functional length of the muscles does not therefore seem to be directly under neuronal control. It appears to be a myogenic response to the amount of passive tension the muscle is subjected to.

Animals↗
PubMed2003

Mechanical effect of muscle spindles in the canine external intercostal muscles.

High-frequency mechanical vibration of the ribcage increases afferent activity from external intercostal muscle spindles, but the effect of this procedure on the mechanical behaviour of the respiratory system is unknown. In the present study, we have measured the changes in external intercostal muscle length and the craniocaudal displacement of the ribs during ribcage vibration (40 Hz) in anaesthetized dogs. With vibration, external intercostal inspiratory activity increased by approximately 50 %, but the respiratory changes in muscle length and rib displacement were unaltered. A similar response was obtained after the muscles in the caudal segments of the ribcage were sectioned and the caudally oriented force exerted by these muscles on the rib was removed, thus suggesting that activation of external intercostal muscle spindles by vibration generates little tension. Prompted by this observation, we also examined the role played by the external intercostal muscle spindles in determining the respiratory displacement of the ribs during breathing against high inspiratory airflow resistances. Although resistances consistently elicited prominent reflex increases in external intercostal inspiratory activity, the normal inspiratory cranial displacement of the ribs was reversed into an inspiratory caudal displacement. Also, this caudal rib displacement was essentially unchanged after section of the external intercostal muscles, whereas it was clearly enhanced after denervation of the parasternal intercostals. These findings indicate that stretch reflexes in external intercostal muscles confer insufficient tension on the muscles to significantly modify the mechanical behaviour of the respiratory system.

Airway Obstruction↗
PubMed2006

Impaired overload-induced muscle growth is associated with diminished translational signalling in aged rat fast-twitch skeletal muscle.

Impaired overload-induced protein synthesis and growth in aged fast-twitch skeletal muscle may result from diminished responsiveness of signalling intermediates controlling protein translation. Yet, potential age-related signalling decrements have never been examined in direct parallel with impaired overload-induced muscle growth in any model. To this end, we used Western blotting to examine the contents and phosphorylation states of mammalian target of rapamycin (mTOR) and its downstream translational signalling intermediates, 70 kDa ribosomal protein S6 kinase (S6k), ribosomal protein S6 (rpS6), eukaryotic elongation factor 2 (eEF2), and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), in conjunction with impaired growth in 1 week overloaded fast-twitch plantaris muscles (via unilateral gastrocnemius ablation) of old (O; 30 months) versus young adult (YA; 8 months) male Fischer344 x Brown Norway rats. The significantly (P <or= 0.05) diminished growth (assessed by total muscle protein content) in overloaded O muscles (5.6 +/- 1.7 versus 19.3 +/- 2.9% in YA) was accompanied by significant impairments in the phosphorylation states of mTOR (Ser2448), S6k (impaired at the mTOR-specific Thr389 residue but not at Thr421/Ser424), rpS6 (Ser235/236) and 4E-BP1 (gel shift), as well as deficits in total eEF2 accretion. Moreover, in overloaded muscles across both age groups, phospho-S6k at Thr389 (but not at Thr421/Ser424), 4E-BP1 phosphorylation status, and total eEF2 accretion were all positively correlated with percentage muscle hypertrophy, and negatively correlated with the phosphorylation (Thr172) of 5'-AMP-activated protein kinase (AMPK; which inhibits translational signalling and protein synthesis in young muscle at rest). As previously published by ourselves, AMPK was hyperphosphorylated in O versus YA muscles used in the current investigation. The present results provide solid evidence that impaired overload-induced growth in aged fast-twitch muscle may partly result from multiple-level decrements in signalling pathway(s) controlling protein translation, and also provide an initial indication that AMPK hyperactivation with age may potentially lie upstream of these decrements.

Adaptation, Physiological↗
PubMed1980

Force development of fast and slow skeletal muscle at different muscle lengths.

It is known that the behavior of fast and slow skeletal muscles differs, but a comparison between fast and slow muscles with different stimulation patterns at various muscle lengths is lacking. The twitch, tetanus, and double pulse responses with a number of interval times have been investigated for a fast (EDL) and a slow (soleus) muscle of the rat at three muscle lengths (in vivo, at 37 degrees C, pentobarbital sodium anesthesia). The twitches of EDL and soleus change with muscle length, but the relative form of the ascending phase is independent of muscle length. The tetanus amplitude is independent of the muscle length over a considerable length range below the optimum twitch length. The form of the ascending phases of EDL-tetanus and double pulse responses (with certain interval times between the stimuli) varies with muscle length in contrast with the comparable soleus force patterns. The maximum slope in the descending phase of all contraction patterns decreases with increasing muscle length above the optimum twitch length.

Action Potentials↗
PubMed2000

Elevated intramuscular concentration of bradykinin in jaw muscle increases the fusimotor drive to neck muscles in the cat.

Patients suffering from temporomandibular dysfunction exhibit clinical findings such as fatigue, painful muscles, and muscles that are tender to palpation, not only in the temporomandibular area, but also in the neck/shoulder region. The mechanisms behind this are not known, although previous studies of similar spreading phenomena have revealed a possible involvement of the fusimotor system. In the present study, we evaluated the activity of this system by recording the activity of muscle spindle afferents from dorsal neck muscles after intramuscular injections of 6 microg to 25 microg bradykinin in the ipsilateral masseter muscle. A total of 23 muscle spindle afferents from the trapezius and splenius muscles was recorded at the C3-C4 level in 7 adult cats anesthetized with alpha-chloralose. Of these 23 afferents, 17 (74%) showed significantly different responses to bradykinin injections compared with control injections (dissolving agent, Tyrode), and the majority of the effects were compatible with an increased static fusimotor drive to the muscle spindle system. Thus, the results demonstrate potent reflex connections from groups III and IV masseter muscle afferents to fusimotor neurones on the C3-C4 level. It is concluded that the fusimotor system might play a significant role in the mechanisms behind the spread of muscle pain and tension from the temporomandibular region to the neck.

Afferent Pathways↗
PubMed2006

Insulin resistance accelerates muscle protein degradation: Activation of the ubiquitin-proteasome pathway by defects in muscle cell signaling.

Conditions such as acidosis, uremia, and sepsis are characterized by insulin resistance and muscle wasting, but whether the insulin resistance associated with these disorders contributes to muscle atrophy is unclear. We examined this question in db/db mice with increased blood glucose despite high levels of plasma insulin. Compared with control littermate mice, the weights of different muscles in db/db mice and the cross-sectional areas of muscles were smaller. In muscle of db/db mice, protein degradation and activities of the major proteolytic systems, caspase-3 and the proteasome, were increased. We examined signals that could activate muscle proteolysis and found low values of both phosphatidylinositol 3 kinase (PI3K) activity and phosphorylated Akt that were related to phosphorylation of serine 307 of insulin receptor substrate-1. To assess how changes in circulating insulin and glucose affect muscle protein, we treated db/db mice with rosiglitazone. Rosiglitazone improved indices of insulin resistance and abnormalities in PI3K/Akt signaling and decreased activities of caspase-3 and the proteasome in muscle leading to suppression of proteolysis. Underlying mechanisms of proteolysis include increased glucocorticoid production, decreased circulating adiponectin, and phosphorylation of the forkhead transcription factor associated with increased expression of the E3 ubiquitin-conjugating enzymes atrogin-1/MAFbx and MuRF1. These abnormalities were also corrected by rosiglitazone. Thus, insulin resistance causes muscle wasting by mechanisms that involve suppression of PI3K/Akt signaling leading to activation of caspase-3 and the ubiquitin-proteasome proteolytic pathway causing muscle protein degradation.

3T3-L1 Cells↗
PubMed2006

Comparison of prenatal muscle tissue expression profiles of two pig breeds differing in muscle characteristics.

The objective of this study was to compare purebred Duroc and Pietrain prenatal muscle tissue transcriptome expression levels at different stages of prenatal development to gain insight into the differences in muscle tissue development in these pig breeds. Commercial western pig breeds have been selected for muscle growth for the past 2 decades. Pig breeds differ for their muscle phenotypes (i.e., myofiber numbers and myofiber types). Duroc and Pietrain pig breeds are extremes; Duroc pigs have redder muscle fiber types with more intramuscular fat, and Pietrain pigs have faster-growing and whiter muscle fiber types. Pietrain pigs are more muscular than Duroc pigs, whereas Duroc pigs are fatter than Pietrain pigs. The genomic background underlying these breed-specific differences is poorly known. Myogenesis is a complex exclusive prenatal process involving proliferation and differentiation (i.e., fusion) of precursor cells called myoblasts. We investigated the difference in the prenatal muscle-specific transcriptome profiles of Duroc and Pietrain pigs using microarray technology. The microarray contained more than 500 genes affecting myogenesis, energy metabolism, muscle structural genes, and other genes from a porcine muscle cDNA library. The results indicated that the expression of the myogenesis-related genes was greater in early Duroc embryos than in early Pietrain embryos (14 to 49 d of gestation), whereas the opposite was found in late embryos (63 to 91 d of gestation). These findings suggest that the myogenesis process is more intense in early Duroc embryos than in Pietrain embryos but that myogenesis is more intense in late Pietrain fetuses than in Duroc fetuses. Transcriptomes of muscle structural genes followed that pattern. The energy metabolism genes were expressed at a higher level in prenatal Pietrain pigs than in prenatal Duroc pigs, except for d 35, when the opposite situation was found. Fatty acid metabolism genes were expressed at a higher level in early (14 to 49 d of gestation) Duroc embryos than in Pietrain embryos. Better understanding of the genomic regulation of tissue formation leads to improved knowledge of the genome under selection and may lead to directed breed-specific changes in the future.

Animals↗
PubMed1989

Continuous electromyographic recordings of pharyngeal muscle activity in normal and previously denervated muscles in dogs.

Continuous electromyographic recordings of pharyngeal muscle activity were made in 5 clinically normal control dogs and in 7 dogs 3 years after partial denervation of the pharyngeal muscles. Electromyographic recordings were made of the sequence of actions of each muscle and of the combined muscle activity, at rest and during swallowing of food. During 30-second periods, the recordings were digitalized and stored on diskette for further analysis. All control dogs had a distinct pattern of muscle activity during swallowing, the onset being in a constant order (hyopharyngeal, thyropharyngeal, and cricopharyngeal) and bilaterally synchronous. While eating, each dog had about 5 to 12 short periods of synchronous activity in each muscle, between the swallowing actions. During the resting period, there were longer periods of activity, which were synchronous with respiration. In each denervated dog, there were normal and irregular swallowing actions. Swallowing activity was recognized, but the sequence of hyopharyngeal, thyropharyngeal, and cricopharyngeal muscle activity was irregular and different from that in control dogs. Partial denervation of the pharyngeal muscles does not seriously impair motor activity of the muscles, but does alter the sequence of activity in the pharyngeal muscles during swallowing.

Animals↗
PubMedDate not supplied

Factors affecting the integrity of latissimus dorsi muscle grafts: implications for cardiac assistance from skeletal muscle.

BACKGROUND: Severe latissimus dorsi muscle damage may compromise cardiomyoplasty performance. We analyzed factors underlying the damage produced in 20 sheep latissimus dorsi muscles by isolating the influences of electrical stimulation, mobilization (with some loss of vascular supply), loss of normal resting tension, or a combination of these. METHODS: In group I (n = 3), the muscle was mobilized except for its neurovascular pedicle and reattached at normal resting length. In group II (n = 3), the muscle was mobilized and reattached at about 80% of resting length. Groups III (n = 6) and IV (n = 4) were as groups I and II except that continuous indirect stimulation at 2 Hz was added after 2 weeks. In group V (n = 4), the undisturbed muscle received stimulation alone. After 10 to 12 weeks, muscle samples were taken for morphometric analysis. RESULTS: Loss of resting muscle tension appeared to be the single most damaging intervention, though mobilization and stimulation had further deleterious effects. The worst damage was seen when all three factors were combined, when 60% of the muscle cross section was occupied by connective tissue and fat. The changes were significantly more severe in the distal than in the proximal part of the muscle, implicating ischemia as a contributory factor. CONCLUSIONS: Fiber damage reduces the effectiveness of muscle grafts used for cardiac assistance and merits further systematic investigation.

Adipose Tissue↗
PubMed1996

Muscle growth and muscle function: a molecular biological perspective.

Molecular biological methods are pervading all biomedical fields and it is likely that they will soon introduce new techniques to veterinary diagnostics and have a major impact on food and fibre production in animal agriculture. The ability to manipulate muscle growth and phenotype will present new ethical problems, particularly if the techniques are used to manipulate muscle development in greyhounds and racehorses where the financial rewards could be very substantial. Muscle has been a useful tissue for the study of the molecular control of tissue development because terminal differentiation results in the production of large quantities of highly specialised proteins. Now that the functional anatomy of structural genes in muscle is being elucidated, a coherent picture is beginning to emerge of the way in which post-natal muscle growth and phenotype are regulated at the gene level. The hormones and growth factors involved in regulating the quantitative and qualitative changes in gene expression are now better understood, together with the ability of the tissue to adapt to physical signals and hence new activity patterns. The myosin heavy chain isoform genes which encode the myosin cross-bridges (the force generators for muscular contraction) exist as a large multigene family. The contractility and other characteristics of muscle depend to a large extent on the differential expression of members of this and other gene families. Muscle fibres adapt for increased power output by expressing a subset of "fast' genes and for increased economy of action by expressing a slow subset of genes and producing more mitochondria. With the increasing understanding of gene expression in muscle, there are prospects for manipulating the mass, contractility and other characteristics of muscle and also to change its phenotype and understand certain disease states.

Agriculture↗
PubMed2004

Androgen receptor regulates expression of skeletal muscle-specific proteins and muscle cell types.

C2C12 myoblasts expressing the androgen receptor (AR) were used to analyze the role of androgen-AR signaling pathway in skeletal muscle development. Marked up-regulation of AR expression was observed in differentiated myotubes. A nuclear run-on transcription assay demonstrated that transcription of the AR gene is increased during skeletal muscle cell differentiation. Regulation of skeletal muscle-specific protein expression by the androgen-AR signaling pathway was further analyzed using quadriceps skeletal muscle from wild-type (WT) and AR knock-out (ARKO) male mice. A histological analysis of quadriceps skeletal muscle indicates no morphological differences between ARKO and WT mice. However, the androgen-AR signaling pathway increases expression of slow-twitch-specific skeletal muscle proteins and downregulates fast-twitch-specific skeletal muscle proteins, resulting in an increase of slow-twitch muscle fiber type cells in quadriceps muscle.

Animals↗
PubMed1998

Curvature of Swimming Fish Midlines as an Index of Muscle Strain Suggests Swimming Muscle Produces Net Positive Work.

The axial muscle used in steady swimming by fish is geometrically complex and this has required the study of in vivo muscle swimming mechanics to be done with largely inferential techniques. Currently there is some debate concerning the variation in muscle function in different regions of the body, and the importance of negative work production by muscles in posterior locations. We have used video taped kinematics of steady swimming in mackerel and then analysed the lateral flexion of the body that is thought to reflect the cycle of length change in the axial muscles. A comparison of several of the techniques used in the past to estimate muscle length changes are shown not to be equivalent. Specifically, we find that peak values of lateral deflection of the body are not correlated in time or axial position with peaks in curvature of the body midline. This is important because the timing of the muscle strain cycle is often inferred from such information. Having documented this observation in a swimming mackerel, we use analytical geometry to show that this result is a consequence of the curves that describe swimming fish midlines. Since this observation is shown to be the geometric consequence of an amplitude envelope that is not constant, it should therefore apply to other animals that propel themselves with axial undulations of increasing amplitude. Our minor result is that care must be taken when estimating the phase of swimming muscle strain from kinematics. Our major results is that appreciation of the geometric character of the kinematics these fish adopt may resolve much of the current debate concerning the mechanical performance of swimming muscle in fish. Specifically, using our estimate of the phase of muscle shortening and data on EMG timing in the mackerel we conclude that all axial muscles are activated before peak length and in a manner that should produce net positive work within each shortening cycle.Copyright 1998 Academic Press

Journal Article↗
PubMed2004

The ultrastructure of locust pleuroaxillary "steering" muscles in comparison to other skeletal muscles.

The ultrastructure of locust muscles with different function is examined: the pleuroaxillary flight steering muscle is compared with a typical flight (power muscle) and a typical leg muscle, in particular with respect to sarcomere length, tracheation, mitochondria, and sarcoplasmatic reticulum. The pleuroaxillary muscle exhibits some features characteristic of flight muscles but most of the ultrastructure resembles that of leg muscles. This is in agreement with the innervation of this muscle by an octopaminergic neuron, which also innervates leg muscles but no other flight muscles. It also supports the hypothesis that octopaminergic neurons are important metabolic regulators and that the above muscle types exhibit important differences in energy metabolism.

Journal Article↗