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Histological Changes in Skeletal Muscle During Death by Drowning: An Experimental Study. Am J Forensic Med Pathol 2016; 37:118-26. [PMID: 27043461 DOI: 10.1097/paf.0000000000000233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A diagnosis of drowning is a challenge in legal medicine as there is generally a lack of pathognomonic findings indicative of drowning. This article investigates whether the skeletal muscle undergoes structural changes during death by drowning. Eighteen Wistar rats were divided into 3 equal groups according to the cause of death: drowning, exsanguination, and cervical dislocation. Immediately after death, samples of the masseter, sternohyoid, diaphragm, anterior tibial, soleus, and extensor digitorum longus muscles were obtained and examined by light and electron microscopy.In the drowning group, all muscles except the masseter displayed scattered evidence of fiber degeneration, and modified Gomori trichrome staining revealed structural changes in the form of abnormal clumps of red material and ragged red fibers. Under the electron microscope, there was myofibrillar disruption and large masses of abnormal mitochondria. In the exsanguination group, modified Gomori trichrome staining disclosed structural changes and mitochondrial abnormalities were apparent under light microscopy; however, there was no evidence of degeneration. No alterations were observed in the cervical dislocation group.As far as we know, this is the first time that these histological findings are described in death by drowning and are consistent with rhabdomyolysis and intense anoxia of skeletal muscle.
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Myosin heavy chain composition of the human sternocleidomastoid muscle. Ann Anat 2012; 194:467-72. [PMID: 22658700 DOI: 10.1016/j.aanat.2012.05.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 04/17/2012] [Accepted: 05/02/2012] [Indexed: 11/24/2022]
Abstract
The sternocleidomastoid (SCM) muscle is one of the neck muscles responsible for head posture and control of head movement. It functions in rotation, inclination, protraction, extension and flexion of the head, whilst chewing and in exerting increased respiratory efforts. This study is the first one describing the myosin heavy chain (MyHC) isoform composition of the SCM muscle of presumably healthy young males for the purpose of better understanding the contractile properties of the muscle as well as to help in evaluation of pathologically altered structure of the muscle. Autopsy samples were processed immunohistochemically to reveal the MyHC isoform composition. The muscle fibres expressed MyHC-1 (31.5%), -2a (29.7%) and -2x (4.3%) or co-expressed MyHC-2a with MyHC-2x (26.8%), MyHC-1 with MyHC-2a (4.1%) and/or MyHC-1, -2a with -2x (1.1%). In addition to the MyHC isoforms, characteristic of adult limb muscles, a very low percentage of muscle fibres (0.2-2.7%) expressed MyHC-neo, which is normally not found in adult limb muscles. Only two samples exhibited MyHC-neo at a rather higher percentage (6.3% and 7.5%) of muscle fibres. The high share of hybrid fibres and the presence of MyHC-neo in the SCM muscle differ from that of adult limb muscles where hybrid fibres are rare and the expression of immature MyHC isoforms occurs only in pathological or experimental conditions. Since the SCM muscle shares the same embryogenic potential as limb muscles, its distinct MyHC expression appears to be associated with twin innervation and with the intrinsic specialisation to perform multiple functions.
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Punga AR, Maj M, Lin S, Meinen S, Rüegg MA. MuSK levels differ between adult skeletal muscles and influence postsynaptic plasticity. Eur J Neurosci 2011; 33:890-8. [PMID: 21255125 DOI: 10.1111/j.1460-9568.2010.07569.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Muscle-specific tyrosine kinase (MuSK) is involved in the formation and maintenance of the neuromuscular junction (NMJ), and is necessary for NMJ integrity. As muscle involvement is strikingly selective in pathological conditions in which MuSK is targeted, including congenital myasthenic syndrome with MuSK mutation and MuSK antibody-seropositive myasthenia gravis, we hypothesized that the postsynaptic response to MuSK-agrin signalling differs between adult muscles. Transcript levels of postsynaptic proteins were compared between different muscles in wild-type adult mice. MuSK expression was high in the soleus and sternomastoid muscles and low in the extensor digitorum longus (EDL) and omohyoid muscles. The acetylcholine receptor (AChR) α subunit followed a similar expression pattern, whereas expression of Dok-7, Lrp4 and rapsyn was comparable between the muscles. We subsequently examined muscles in mice that overexpressed a miniaturized form of neural agrin or MuSK. In these transgenic mice, the soleus and sternomastoid muscles responded with formation of ectopic AChR clusters, whereas such clusters were almost absent in the EDL and omohyoid muscles. Electroporation of Dok-7 revealed its important role as an activator of MuSK in AChR cluster formation in adult muscles. Together, our findings indicate for the first time that adult skeletal muscles harbour different endogenous levels of MuSK and that these levels determine the ability to form ectopic AChR clusters upon overexpression of agrin or MuSK. We believe that these findings are important for our understanding of adult muscle plasticity and the selective muscle involvement in neuromuscular disorders in which MuSK is diminished.
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Affiliation(s)
- Anna R Punga
- Department of Neurobiology/Pharmacology, Biozentrum, University of Basel, Basel, Switzerland.
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Goodman C, Patterson M, Stephenson G. MHC-based fiber type and E-C coupling characteristics in mechanically skinned muscle fibers of the rat. Am J Physiol Cell Physiol 2003; 284:C1448-59. [PMID: 12734106 DOI: 10.1152/ajpcell.00569.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we investigated whether the previously established differences between fast- and slow-twitch single skeletal muscle fibers of the rat, in terms of myosin heavy chain (MHC) isoform composition and contractile function, are also detectable in excitation-contraction (E-C) coupling. We compared the contractile responsiveness of electrophoretically typed, mechanically skinned single fibers from the soleus (Sol), the extensor digitorum longus (EDL), and the white region of the sternomastoid (SM) muscle to t-system depolarization-induced activation. The quantitative parameters assessed were the amplitude of the maximum depolarization-induced force response (DIFR(max); normalized to the maximum Ca(2+)-activated force in that fiber) and the number of responses elicited until the force declined by 75% of DIFR(max) (R-D(75%)). The mean DIFR(max) values for type IIB EDL and type IIB SM fibers were not statistically different, and both were greater than the mean DIFR(max) for type I Sol fibers. The mean R-D(75%) for type IIB EDL fibers was greater than that for type I Sol fibers as well as type IIB SM fibers. These data suggest that E-C coupling characteristics of mechanically skinned rat single muscle fibers are related to MHC-based fiber type and the muscle of origin.
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Affiliation(s)
- Craig Goodman
- Muscle Cell Biochemistry Laboratory, School of Biomedical Sciences, Victoria University, Melbourne City, Melbourne 8001, Australia
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Wieneke S, Stehle R, Li Z, Jockusch H. Generation of tension by skinned fibers and intact skeletal muscles from desmin-deficient mice. Biochem Biophys Res Commun 2000; 278:419-25. [PMID: 11097852 DOI: 10.1006/bbrc.2000.3810] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have investigated the physiological role of desmin in skeletal muscle by measuring isometric tension generated in skinned fibres and intact skeletal muscles from desmin knock-out (DES-KO) mice. About 80% of skinned single extensor digitorum longus (EDL) fibres from adult DES-KO mice generated tensions close to that of wild-type (WT) controls. Weights and maximum tensions of intact EDL but not of soleus (SOL) muscles were lowered in DES-KO mice. Repeated contractions with stretch did not affect subsequent isometric tension in EDL muscles of DES-KO mice. Tension during high frequency fatigue (HFF) declined faster and this deficiency was compensated in DES-KO EDL muscles by 5 mM caffeine which had no influence on HFF in WT EDL. Furthermore, caffeine evoked twitch potentiation was higher in DES-KO than in WT muscles. We conclude that desmin is not essential for acute tensile strength but rather for optimal activation of intact myofibres during E-C coupling.
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Affiliation(s)
- S Wieneke
- Developmental Biology Unit, University of Bielefeld, Bielefeld, D-33501, Germany
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McLoon LK, Falkenberg JH, Dykstra D, Iaizzo PA. Doxorubicin chemomyectomy as a treatment for cervical dystonia: histological assessment after direct injection into the sternocleidomastoid muscle. Muscle Nerve 1998; 21:1457-64. [PMID: 9771670 DOI: 10.1002/(sici)1097-4598(199811)21:11<1457::aid-mus14>3.0.co;2-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The sternocleidomastoid muscle (SCM) is one of the major muscles involved in producing abnormal head position in cervical dystonia patients. This study tested whether doxorubicin chemomyectomy, direct injection of doxorubicin into the SCM to permanently remove muscle fibers, has the potential to be a nonsurgical, permanent treatment for cervical dystonia. The right SCM of rabbits was injected with either 1 or 2 mg doxorubicin. Animals were sacrificed 1-2 months postinjection. The SCM was prepared for histological examination of muscle fiber loss and fiber type composition. In all cases, direct injection of doxorubicin resulted in significant decreases in total muscle cross-sectional areas ranging from 75% up to 98%. Individual myofiber cross-sectional areas were smaller than normal after 2 mg doxorubicin treatment, but similar to normal fiber size after 1 mg doxorubicin. There were increased numbers of myofibers that expressed slow and neonatal myosin heavy chain isoforms in these remaining muscle fibers compared to the untreated SCM on the contralateral side. Developmental myosin heavy chain (MHC) was also present in 53% of the remaining myofibers of the treated muscles. The fiber type composition of muscles contralateral to the doxorubicin injections was compared to the fiber type composition of SCM from normal, untreated controls; no difference was seen in the proportions of fast, slow, and neonatal MHC fiber types in these SCM muscles. In summary, the direct injection of doxorubicin into the SCM resulted in significant muscle loss. This supports the use of doxorubicin chemomyectomy as a potential permanent, nonsurgical treatment for cervical dystonia.
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Affiliation(s)
- L K McLoon
- Department of Ophthalmology, University of Minnesota, Minneapolis 55455, USA
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McLoon LK. Muscle fiber type compartmentalization and expression of an immature myosin isoform in the sternocleidomastoid muscle of rabbits and primates. J Neurol Sci 1998; 156:3-11. [PMID: 9559980 DOI: 10.1016/s0022-510x(98)00011-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The sternocleidomastoid muscle is located in the neck and is both a neck rotator and flexor. Cervical dystonia, a focal dystonia disorder, is characterized by forceful involuntary contraction of a group of neck muscles, usually including the sternocleidomastoid. Little is known about the fiber type composition, fiber type compartmentalization and innervation patterns in this muscle in rabbit and primates. Sternocleidomastoid muscles from rabbit and monkey were analyzed for muscle fiber type composition and number, muscle fiber cross-sectional area and patterns of innervation. The sternocleidomastoid muscle was composed of two distinct regions, or compartments, with different fiber type compositions: an outer or superficial region composed of mostly type 2 myofibers and an inner deep region composed of both type 2 and type 1 myofibers. Neonatal myosin heavy chain isoform was detected in approximately 25% of the myofibers in both regions of the muscle. Neuromuscular junctions were located in seven endplate bands approximately 1-3 cm apart throughout the length of the muscle. There is clear evidence of anatomical subdivisions within this muscle. Not only is there variation in fiber type composition between superficial and deep regions of the muscle, but unlike most other mature skeletal muscles, it continues to express neonatal myosin heavy chain isoform in the adult. The motor program for neck movements is extremely complex, and the histological complexity plays a role in allowing for a continuum of movements of the head and neck, from maintenance of posture to rapid head movements.
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Affiliation(s)
- L K McLoon
- Department of Ophthalmology, University of Minnesota, Minneapolis 55455, USA.
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Cairns SP, Dulhunty AF. High-frequency fatigue in rat skeletal muscle: role of extracellular ion concentrations. Muscle Nerve 1995; 18:890-8. [PMID: 7630351 DOI: 10.1002/mus.880180814] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
High-frequency fatigue (HFF), the decline of force during continuous tetanic stimulation (lasting 4-40 s), was studied in isolated bundles of rat skeletal muscle fibers. HFF was slower in slow-twitch soleus fibers than in fast-twitch red or white sternomastoid fibers; denervation accelerated fatigue in soleus. Maximal 200-mmol/L potassium contractures of normal amplitude were induced in fatigued fibers, suggesting that crossbridge cycling and the voltage activation of excitation-contraction coupling could still occur maximally, but that activation by action potentials was impaired. An increase in [Na+]o slowed HFF, while a small increase in [K+]o or reduction in [Cl(-)]o accelerated HFF. Increasing the tetanic stimulation frequency exacerbated fatigue. Recovery from HFF proceeded rapidly since force increased markedly within a few seconds when stimulation ceased. These results support the hypothesis that a redistribution of Na+, K+, and Cl- across the transverse tubular membranes during repeated action potential activity induces fatigue by reducing the amplitude and conduction of action potentials.
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Affiliation(s)
- S P Cairns
- Muscle Research Group, John Curtin School of Medical Research, Australian National University, Canberra
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Cairns SP, Dulhunty AF. The effects of beta-adrenoceptor activation on contraction in isolated fast- and slow-twitch skeletal muscle fibres of the rat. Br J Pharmacol 1993; 110:1133-41. [PMID: 8298802 PMCID: PMC2175799 DOI: 10.1111/j.1476-5381.1993.tb13932.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. The aim of the experiments was to examined the effects of beta-adrenoceptor activation on twitch and tetanic contractions in fast- and slow-twitch mammalian skeletal muscle fibres. Isometric force was recorded from bundles of intact fibres isolated from the normal and denervated slow-twitch soleus and normal fast-twitch sternomastoid muscles of the rat. 2. Terbutaline (10 microM), a beta 2-adrenoceptor agonist, induced an average 15% potentiation of peak twitch and peak tetanic force in normal soleus fibres and abbreviated twitch and tetanic relaxation. In white- and red-sternomastoid fibres, 10 microM terbutaline potentiated peak twitch force by about 7% and slowed twitch relaxation. 3. The potentiation of twitches and tetani by terbutaline was quantitatively similar in normal and denervated soleus fibres. However, in contrast to the normal soleus, terbutaline slowed twitch relaxation and had no effect on tetanic relaxation in denervated soleus fibres. 4. Adrenaline (10 microM) increased peak tetanic force by about 7% in both normal and denervated soleus fibres. 5. Exposure to (+/-)-propranolol (0.1 microM), a general beta-adrenoceptor blocker, completely abolished the tetanus potentiation by terbutaline. 6. Dibutyryl-cyclic AMP (2 mM) mimicked the effects of 10 microM terbutaline on peak tetanic force and tetanic relaxation in normal and denervated soleus fibres. Dibutyryl-cyclic AMP also potentiated peak twitch force in denervated soleus fibres but only after a brief period of twitch depression: the twitch depression might be due to butyrate. 7. The results suggest that the increase in peak twitch and tetanic force and abbreviation of tetanic relaxation induced by terbutaline depend on the activation of beta-adrenoceptors and a consequent increase in the myoplasmic cyclic AMP concentration.
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Affiliation(s)
- S P Cairns
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T
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Zenker W, Snobl D, Boetschi R. Multifocal innervation and muscle length. A morphological study on the role of myo-myonal junctions, fiber branching and multiple innervation in muscles of different size and shape. ANATOMY AND EMBRYOLOGY 1990; 182:273-83. [PMID: 2268070 DOI: 10.1007/bf00185520] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The dependence of the inner organisation and innervation of a skeletal muscle on its size was studied at the level of single muscle fiber architecture and motor endplate topography in muscles of different size, all of them lacking a tendinous scaffolding. The muscles evaluated in this study were: Mm. sternomastoideus, gracilis and latissimus dorsi of the rat and the M. sternocephalicus of the horse. In these muscles a subdivision into two or more 'innervation-compartments' becomes obvious in fascicles reaching a certain length. This provides the possibility of an almost synchronous activation of the entire muscle by its nerve. At the level of single muscle fiber elements, large numbers of myo-myonal junctions were discernible in many sites. However, unequivocal multiple innervation was found, with several end-plates per single muscle fiber, without the interposition of any junctional structure. Myo-myonal junctions, combined with a characteristic branching pattern of many muscle fibers, and scattered innervation sites, obviously play an important role in the architecture of fan-like muscles lacking a tendinous scaffolding.
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Affiliation(s)
- W Zenker
- Institute of Anatomy, University of Zurich, Switzerland
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12
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Callister RJ, Callister R, Peterson EH. Histochemical classification of neck and limb muscle fibers in a turtle, Pseudemys scripta: a study using microphotometry and cluster analysis techniques. J Morphol 1989; 199:269-86. [PMID: 2468778 DOI: 10.1002/jmor.1051990304] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have attempted to develop an objective, semiquantitative classification of fiber types in turtle neck and limb muscle using microphotometry and multivariate statistical techniques. We first stained serial sections for myosin adenosine triphosphatase (ATPase) (with acid and alkaline preincubation and without preincubation), NADH-diaphorase, and two glycolysis-associated markers, alpha-glycerophosphate dehydrogenase (alpha-GPDH) and glycogen phosphorylase A (GPA). This allowed us to characterize individual muscle fibers in terms of their contraction speed and metabolic properties. Next we used microphotometry to measure the optical density of the reaction product in each fiber, and we subjected the resulting optical density matrix to cluster and discriminant function analyses in order to assign fibers to groups (fiber types) and to determine which stains contribute most to the distinction between groups. As a control, we processed a well characterized mammalian muscle (rat sternomastoid) simultaneously. Our results suggest that both neck and limb muscle in Pseudemys can best be described as falling into three groups: 1) slow oxidative (SO) fibers; 2) fast oxidative glycolytic (FOG) fibers, with relatively high oxidative and glycolytic capacities; and 3) fast glycolytic (Fg) fibers, with low oxidative, low/intermediate alpha-GPDH, and high GPA activities. These three fiber types differ from like-named types in rat muscle both in the pH lability of their myosins and in their metabolic profiles.
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Affiliation(s)
- R J Callister
- Department of Zoological and Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens 45701
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Chua M, Dulhunty AF. Inactivation of excitation-contraction coupling in rat extensor digitorum longus and soleus muscles. J Gen Physiol 1988; 91:737-57. [PMID: 3418320 PMCID: PMC2216151 DOI: 10.1085/jgp.91.5.737] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
K contractures and two-microelectrode voltage-clamp techniques were used to measure inactivation of excitation-contraction coupling in small bundles of fibers from rat extensor digitorum longus (e.d.l.) and soleus muscles at 21 degrees C. The rate of spontaneous relaxation was faster in e.d.l. fibers: the time for 120 mM K contractures to decay to 50% of maximum tension was 9.8 +/- 0.5 s (mean +/- SEM) in e.d.l. and 16.8 +/- 1.7 s in soleus. The rate of decay depended on membrane potential: in e.d.l., the 50% decay time was 14.3 +/- 0.7 s for contractures in 80 mM K (Vm = 25 mV) and 4.9 +/- 0.4 s in 160 mM K (Vm = -3 mV). In contrast to activation, which occurred with less depolarization in soleus fibers, steady state inactivation required more depolarization: after 3 min at -40 mV in 40 mM K, the 200 mM K contracture amplitude in e.d.l. fell to 28 +/- 10% (n = 5) of control, but remained at 85 +/- 2% (n = 6) of control in soleus. These different inactivation properties in e.d.l. and soleus fibers were not influenced by the fact that the 200 mM K solution used to test for steady state inactivation produced contractures that were maximal in soleus fibers but submaximal in e.d.l.: a relatively similar depression was recorded in maximal (200 mM K) and submaximal (60 and 80 mM K) contracture tension. A steady state "pedestal" of tension was observed with maintained depolarization after K contracture relaxation and was larger in soleus than in e.d.l. fibers. The pedestal tension was attributed to the overlap between the activation and inactivation curves for tension vs. membrane potential, which was greater in soleus than in e.d.l. fibers. The K contracture results were confirmed with the two-microelectrode voltage clamp: the contraction threshold increased to more positive potentials at holding potentials of -50 mV in e.d.l. or -40 mV in soleus. At holding potentials of -30 mV in e.d.l. or 0 mV in soleus, contraction could not be evoked by 15-ms pulses to +20 mV. Both K contracture and voltage-clamp experiments revealed that activation in soleus fibers occurred with a smaller transient depolarization and was maintained with greater steady state depolarization than in e.d.l. fibers. The K contracture and voltage-clamp results are described by a model in which contraction depends on the formation of a threshold concentration of activator from a voltage-sensitive molecule that can exist in the precursor, activator, or inactive states.
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Affiliation(s)
- M Chua
- Department of Physiology, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T
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Zenker W, Sandoz PA, Neuhuber W. The distribution of anterogradely labeled I--IV primary afferents in histochemically defined compartments of the rat's sternomastoid muscle. ANATOMY AND EMBRYOLOGY 1988; 177:235-43. [PMID: 3354841 DOI: 10.1007/bf00321134] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The sternomastoid muscle of the rat is divided into a white (dominated by fast-glycolytic twitch fibers) and a red (dominated by fast oxidative-glycolytic twitch fibers, but also containing slow-oxidative twitch fibers) compartment. Previous reports on exclusive location of muscle spindles in the red portion were confirmed. On the basis of anterograde labeling with horseradish peroxidase-wheat germ agglutinine conjugate (WGA-HRP) it was shown in this study that, in addition to muscle spindle compartmentalisation, there was also an exclusive occurrence of tendon organs in the red part of the muscle; moreover, fine afferents (III- and IV-afferents) were mainly distributed to this portion as well. Radioimmunassay studies revealed that this part of the muscle contained twice as much substance P as the white part. It could be shown by acetylcholinesterase (AChE) histochemistry that the myelinated fibers of the white branch to the muscle exclusively displayed high enzyme activity which is characteristic for motor fibers; on the other hand, in the branch to the red portion two classes of AChE-positive fibers were found: a large one with a peak in the alpha-range, and a small one with a peak in the gamma-range. In addition, there was also a group of enzyme-negative (sensory) fibers. These results also indicate the red portion of the sternomastoid muscle to be its "sensory compartment".
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Affiliation(s)
- W Zenker
- Institute of Anatomy, University of Zürich, Switzerland
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Franzini-Armstrong C, Gilly WF, Aladjem E, Appelt D. Golgi stain identifies three types of fibres in fish muscle. J Muscle Res Cell Motil 1987; 8:418-27. [PMID: 2448338 DOI: 10.1007/bf01578431] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Using Golgi infiltration we have studied the structure and disposition of transverse tubules in muscle fibres from the sand dab fin musculature. Three types of fibres differ significantly from each other in the extent and disposition of junctions between transverse tubules and the sarcoplasmic reticulum. These correlate with the three groups of fibres having different relaxation times shown in the accompanying paper (Gilly & Aladjem, 1987). Fibres with very slow relaxation (tonic fibres) correspond to those which have an unusual disposition of T tubules and very rare T-SR junctions. In the fast twitch fibres the peripheral T tubules segments converge into tangentially arranged tubules before joining the plasmalemma.
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Affiliation(s)
- C Franzini-Armstrong
- Department of Anatomy, Medical School, University of Pennsylvania, Philadelphia 19104
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Dulhunty AF, Banyard MR, Medveczky CJ. Distribution of calcium ATPase in the sarcoplasmic reticulum of fast- and slow-twitch muscles determined with monoclonal antibodies. J Membr Biol 1987; 99:79-92. [PMID: 2963132 DOI: 10.1007/bf01871228] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Four monoclonal antibodies against the calcium ATPase in sarcoplasmic reticulum (SR) of rabbit fast-twitch skeletal muscle were characterized using SDS-PAGE, Western blots and immunofluorescence. The ultrastructural distribution of the antigens was determined using post-embedding immunolabeling. The antibodies recognized the calcium ATPase in the SR but not in transverse (T-) tubule or plasma membranes. The antibody, D12, had the same binding affinity for the calcium ATPase from fast-twitch (rabbit sternomastoid) and slow-twitch (rabbit soleus) fibers and the affinity fell by 30% after fixation for electron microscopy in both types of muscle fiber. Ultrastructural studies revealed that the density of D12 antibody binding to the terminal cisternae membrane of extensor digitorum longus (edl) and sternomastoid fibers was on average seven times greater than in the slow-twitch soleus and semimembranosus fibers. Since the affinity of the ATPase for the antibody was the same in SR from fast- and slow-twitch muscles, the concentration of calcium ATPase in the terminal cisternae membrane of fast-twitch fibers was seven times greater than in slow-twitch fibers. This conclusion was supported by the fact that the concentration of calcium ATPase in light SR membranes was six times greater in SR from fast-twitch fibers than in SR from slow-twitch fibers. The results provide strong evidence that the different calcium accumulation rates in mammalian fast- and slow-twitch muscles are due to different concentrations of calcium ATPase molecules in the SR membrane.
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Affiliation(s)
- A F Dulhunty
- Department of Physiology, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T
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17
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Brichta AM, Callister RJ, Peterson EH. Quantitative analysis of cervical musculature in rats: histochemical composition and motor pool organization. I. Muscles of the spinal accessory complex. J Comp Neurol 1987; 255:351-68. [PMID: 2950139 DOI: 10.1002/cne.902550304] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this paper we characterize the architecture and segmental innervation, histochemical composition, muscle spindle populations, and motor pool organization of rat spinal accessory (SA) muscles: sternomastoid (SM), cleidomastoid (CM), cleidotrapezius (CT), and acromiotrapezius (AT). We also consider whether individual rat neck muscles are supplied by more than one population of motor neurons as they are in turtles and cats and whether in SA muscles motor neuron size scales with target muscle fiber type. SM, CM, and CT are ventral, parallel strap muscles. Each can be divided into grossly visible white and red compartments. AT is a dorsolateral sheetlike muscle that shows no gross compartmentalization. All four muscles are dominated by fast-twitch glycolytic (FG) and fast oxidative glycolytic (FOG) fibers, and FG fibers are significantly more numerous than the FOG type in three out of four muscles. Thus SA muscles in rats appear to be specialized for rapid, phasic head movements. Topographical analyses revealed that there is a striking compartmentalization of fiber types in the ventral muscles that corresponds to the red and white segments seen grossly. Spindles are found only in regions containing slow-twitch oxidative (SO) fibers. Cross-muscle comparisons indicate that there are significant differences between SA muscles in their fiber type composition. The motor pools of SA muscles form a single column from lower medulla to C5. Rostral cells lie dorsomedially in the ventral horn and, at the C1/C2 junction, the column shifts ventrolaterally. Within this column, each motor pool occupies a characteristic rostrocaudal position in the order SM:CM:CT:AT. Thus SM and (in part) CM motor neurons lie more medially than cells supplying the trapezius complex, suggesting that they may be under different patterns of synaptic drive. We saw no evidence that rat SA muscles are supplied by more than one population of motor neurons. Direct comparisons between the soma sizes of motor neurons that supply muscles or parts of muscles with significantly different histochemical compositions indicate that these size differences are in the direction predicted from their histochemical profiles, thus suggesting that in these muscles motor neuron soma size may scale with muscle fiber type.
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Mrázková O, Grim M, Carlson BM. Enzymatic heterogeneity of the capillary bed of rat skeletal muscles. THE AMERICAN JOURNAL OF ANATOMY 1986; 177:141-8. [PMID: 2431612 DOI: 10.1002/aja.1001770203] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This study of the capillaries in rat skeletal muscle involved the use of a histochemical method that allows one to distinguish between arterial and venous portions of capillaries. Under controlled staining conditions, the arterial portion of the capillary bed reacts positively for alkaline phosphatase (AP) activity, and the venous portion is positive for dipeptidyl peptidase IV (DPP IV) activity. A short transitional capillary segment is positive for the activity of both enzymes. Capillaries of the normal soleus muscle and the red and white portions of the sternomastoid muscle have been quantitatively analyzed. Quantitative data demonstrated differences in capillary dimensions among the muscles studied. Capillaries of the white part of the sternomastoid were the longest, and they had the shortest DPP IV-positive segment (8% of the total capillary length). Capillaries of the soleus muscle were the shortest, and they also had short DPP IV-positive segments (16%). In contrast, the DPP IV-positive segments of the red part of the sternomastoid occupied 60% of the total capillary length. Survey cross sections reveal a mosaic distribution of patches of capillaries stained for AP and DPP IV activity. This study reveals that within given bundles of muscle fibers, the capillaries that run parallel to the muscle fibers are aligned relative to one another in such a manner that their arterial and venous segments are in register.
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Dulhunty AF. A freeze-fracture study of extensor digitorum longus and soleus muscle fibers from thyrotoxic rats. JOURNAL OF ULTRASTRUCTURE AND MOLECULAR STRUCTURE RESEARCH 1986; 94:121-30. [PMID: 3782925 DOI: 10.1016/0889-1605(86)90058-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Freeze-fracture methods were used to study the sarcoplasmic reticulum and surface membranes in muscles from rats after chronic administration of triiodothyronine (150 micrograms/kg daily, for 1 to 20 days). The major effect of the hormone on the sarcoplasmic reticulum was to increase the numbers of indentations in the terminal cisternae in parallel with an increase in the speed of the isometric twitch. The indentations increased from 7.3 +/- 0.2 to 10.6 +/- 0.1 (mean +/- 1 SEM)/micron of terminal cisternae in the fast-twitch extensor digitorum longus (EDL) and from 0.9 +/- 0.1 to 4.4 +/- 0.1/micron in slow-twitch soleus fibers. The increase in indentation density in both types of muscle occurred within 10 days of the commencement of hormone injection. During the same period there was a small reduction in the density of intramembrane particles in the plasmalemma and a significant increase in the number of caveolae, from 14.6 +/- 0.25 to 20.4 +/- 0.3/micron2 in EDL fibers, and from 22.9 +/- 0.3 to 28.6 +/- 0.3/micron2 in soleus. The increase in caveolae density was coincident with an increase in the area of T-tubule membrane. The results provide further evidence that the indentations in the terminal cisternae play a functional role in muscle activation and that the caveolae are the surface openings of transverse tubules.
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Abstract
The sternomastoid muscle of the rat can be subdivided into a "white" and "red" portion. The red portion predominantly contains type IIA fibers and the white portion type IIB fibers. Fiber bundles were dissected from the two parts of the muscle and their dynamic properties determined; both showed "fast-twitch" type characteristics. Small, but significant, differences were found in their isometric properties. Their force-velocity relationships were identical, although the maximum speed of sarcomere shortening (about 40 microns s-1) was significantly less than that of other fast-twitch rat muscles. Other differences in the respective force-length relations at different temperatures were noted. The desirability of pursuing these investigations on identified single fibers is emphasized.
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Dulhunty AF. Excitation-contraction coupling and contractile properties in denervated rat EDL and soleus muscles. J Muscle Res Cell Motil 1985; 6:207-25. [PMID: 4031051 DOI: 10.1007/bf00713062] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The long-term (up to ten weeks) effects of denervation on isometric tension and potassium (K) contractures were studied in isolated bundles of fibres from rat extensor digitorum longus (EDL) and soleus muscles, at 21 degrees C, bathed in solutions with low concentrations of chloride ions (to reduce the effects of high membrane chloride conductance). The usual increases in twitch time course and twitch for tetanus ratio were attributed to changes in excitation-contraction coupling because both developed between one to three weeks after denervation. Transient changes during the first week in the time course of the twitch and twitch to tetanus ratio in EDL, and post-tetanic twitch size and specific tension in both muscles, were attributed to the surface membrane electrical properties which are maximally altered within three days after denervation. In contrast to results obtained in solutions of normal chloride concentration, the resting membrane potentials of chronically denervated fibres were hyperpolarized and spontaneous action potentials and fibrillations were seen. The time to the peak of the K-contracture was faster than normal and very slow inactivation kinetics appeared in the decay phase. Mechanical repriming was normally slower in EDL than in soleus but similar rates were seen in the two muscles after denervation. These changes in the K-contracture were not due to a change in the relationship between membrane potential and potassium ion concentration. It is concluded that denervation caused changes in the kinetics of mechanical activation, inactivation and repriming and that these aspects of excitation-contraction coupling are normally controlled by an influence of the motor nerve.
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Dulhunty A, Carter G, Hinrichsen C. The membrane capacity of mammalian skeletal muscle fibres. J Muscle Res Cell Motil 1984; 5:315-32. [PMID: 6746892 DOI: 10.1007/bf00713110] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Membrane capacity was measured as a function of fibre diameter in mammalian skeletal muscle fibres under normal conditions and under conditions designed to reduce the membrane chloride conductance, i.e. in solutions in which chloride ions were replaced by sulphate or methylsulphate ions, or in normal Krebs solutions containing 2,4-dichlorophenoxyacetic acid (2.5 mM). The experiments were done on rat sternomastoid, extensor digitorum longus and soleus muscle fibres. The average membrane capacity of fibres in each muscle was greater than normal when chloride conductance was reduced and the slope of the relationship between membrane capacity and fibre diameter increased. The results were consistent with the hypothesis that the space constant of the transverse tubule system in mammalian fibres is normally short because the transverse tubule membrane has a high chloride conductance. The experimental results imply that the space constant of the transverse tubule system was less than 40 microns for fibres in normal Krebs solution and greater than 100 microns for fibres with low membrane chloride conductance. The space constant was calculated using measured geometrical parameters of the transverse tubule, and measured membrane conductance, and the values were close to 20 microns for fibres in normal Krebs solution and between 50 and 120 microns for fibres with low chloride conductance.
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Dulhunty A, Valois A. Indentations in the terminal cisternae of amphibian and mammalian skeletal muscle fibers. JOURNAL OF ULTRASTRUCTURE RESEARCH 1983; 84:34-49. [PMID: 6411932 DOI: 10.1016/s0022-5320(83)90084-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Indentations (hillocks and dimples) in the terminal cisternae of mammalian and amphibian skeletal muscle fibers were studied using freeze-fracture and serial thin-section techniques. The structures were seen in all muscles and had a regular separation from each other and from the T-tubule. Indentations were smaller than fenestrations and formed concavities in, but not macromolecular pores through, the terminal cisternae. The average numbers of indentations in rat muscles (measured along the length of the terminal cisternae, within 150 nm of the triadic junction) varied from 0.9 per micrometer in soleus fibers to 9.6 per micrometer in posterior cricoarytenoid fibers. The average numbers in amphibian sartorius fibers varied from 1.6 to 3.6 per micrometer in muscles from different species. The regular alignment of the indentations along the triad, as well as a close correlation between their numbers and the contractile properties of the muscle, suggest that they function in contractile activation and may represent sites of calcium release from the terminal cisternae.
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Hinrichsen C, Dulhunty A. The contractile properties, histochemistry, ultrastructure and electrophysiology of the cricothyroid and posterior cricoarytenoid muscles in the rat. J Muscle Res Cell Motil 1982; 3:169-90. [PMID: 6213635 DOI: 10.1007/bf00711941] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The contractile, histochemical, morphological and electrophysiological properties of two rat laryngeal muscles, the cricothyroid and posterior cricoarytenoid, have been measured. Both muscles act during respiration to maintain upper airway patency and an even distribution of air in the lungs. The cricothyroid and posterior cricoarytenoid are fast-twitch muscles, having contraction times of 3.4 and 7.2 ms respectively, high myosin ATPase activity, abundant sarcoplasmic reticulum (with average volumes of 9% and 15%, respectively, of the fibre volume) and T-system membrane (with average areas of 0.4 and 0.5 micron 2 micron -3 of fibre). The large areas of T-tubule membrane are reflected in the average specific membrane capacities of 6.5 muF cm-2 to 10.5 muF cm-2, which are high considering the small diameter of the fibres (20-30 micron). Of the two muscles, the posterior cricoarytenoid has the faster contraction time and the more abundant sarcoplasmic reticulum content. In addition, the posterior cricoarytenoid is less resistant to fatigue and demonstrates lower succinic dehydrogenase activity. The fatigability of this muscle, coupled with its general lack of functional reserve, suggest that its failure may contribute to upper airway obstruction during respiratory distress.
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Abstract
1. Mouse extensor digitorum longus and soleus muscles respond to a sudden maintained increase in external K ion concentration with a fast contracture which inactivates and is followed by a slow contracture. 2. The slow contracture could not be selectively eliminated by altering the tonicity, ionic strength, anionic composition or buffer system of the external solution and depended only on the increase on external potassium concentration. The slow contracture differed from the fast K contracture in its time course, temperature sensitivity, fibre type dependence, and inactivation kinetics. The fast and slow contractures were similarly altered by changes in external anion species, by changes in external divalent cations, and by the presence of 20 mM-caffeine. 3. The mechanism and functional significance of the slow contracture are obscure. The results suggest that its generation is not identical to that of the fast contracture, but may depend, in part, upon the normal activation processes.
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Dulhunty AF. Potassium contractures and mechanical activation in mammalian skeletal muscles. J Membr Biol 1980; 57:223-33. [PMID: 7205947 DOI: 10.1007/bf01869590] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Potassium (K-) contractures were recorded from slow-twitch (mouse soleus and fast-twitch (mouse extensor digitorum longus (EDL) and rat sternomastoid) muscles. The mouse limb muscles responded to a maintained increase in external potassium concentration with a rapid increase in tension (fast contracture) which inactivated and was followed by a slow contracture. Rat sternomastoid muscles responded with fast contractures only. The threshold potassium concentration for contraction was higher in fast-twitch muscles than in soleus muscles, at 22 and at 37 degrees C. After corrections had been made for the more rapid depolarization of soleus fibers, the threshold potential for soleus fiber contraction was 15mV closer to the resting membrane potential than the threshold for fast-twitch fiber contraction. The K-contracture results were confirmed by two microelectrode voltage-clamp experiments. Activation of fast twitch fibers required depolarizing pulses that were 15 to 20mV greater than the pulses required to activate soleus fibers. When the time courses of K-contractures were compared it was evident that inactivation with prolonged depolarization was much faster in the fast-twitch muscles than in the soleus muscles. The results suggest that the voltage dependence and kinetics of the process coupling T-tubule depolarization with calcium release from the sarcoplasmic reticulum may depend on fiber atype in mammalian skeletal muscle.
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Abstract
(1) The effects of glycerol-treatment on the ultrastructure, tension, and electrical properties of rat sternomastoid muscle fibers are described. (2) The effect upon the ultrastructure of fibers differed from that previously reported for amphibian fibers, in that the sarcoplasmic reticulum, as well as the T-system, was disrupted. (3) Tension (tension (tetanus and K-contracture) was abolished when preparations were returned to normal Krebs after exposure to a glycerol-Krebs solution (exposure periods were 1 hr in 200--350 mM-glycerol or 10--60 min in 350 mM-glycerol), although fibers had normal resting membrane potentials and action potentials. (4) Fibers treated for 1 hr with 350 mM-glycerol were detubulated when returned to normal Krebs. Specific membrane capacity was reduced and exogenous horseradish peroxidase (HRP) did not penetrate the T-system. (5) Fibers were not detubulated after treatment for 1 hr with 200 to 300 mM-glycerol or after treatment for 10 to 30 min with 350 mM glycerol. Specific membrane capacity and resistance were normal and HRP entered the T-system. (6) Ultrastructural disruption of the triad junction became progressively more extensive with increasing glycerol concentration used and may be responsible for uncoupling.
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Gottschall J, Zenker W, Neuhuber W, Mysicka A, Müntener M. The sternomastoid muscle of the rat and its innervation. Muscle fiber composition, perikarya and axons of efferent and afferent neurons. ANATOMY AND EMBRYOLOGY 1980; 160:285-300. [PMID: 6450556 DOI: 10.1007/bf00305109] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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