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Venturelli M, Saggin P, Muti E, Naro F, Cancellara L, Toniolo L, Tarperi C, Calabria E, Richardson RS, Reggiani C, Schena F. In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans. Acta Physiol (Oxf) 2015; 215:58-71. [PMID: 25965867 DOI: 10.1111/apha.12524] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 02/06/2015] [Accepted: 05/07/2015] [Indexed: 12/17/2022]
Abstract
AIM To parse out the impact of advanced ageing and disuse on skeletal muscle function, we utilized both in vivo and in vitro techniques to comprehensively assess upper- and lower-limb muscle contractile properties in 8 young (YG; 25 ± 6 years) and 8 oldest-old mobile (OM; 87 ± 5 years) and 8 immobile (OI; 88 ± 4 years) women. METHODS In vivo, maximal voluntary contraction (MVC), electrically evoked resting twitch force (RT), and physiological cross-sectional area (PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies of the vastus lateralis and biceps brachii facilitated the in vitro assessment of single fibre-specific tension (Po). RESULTS In vivo, compared to the young, both the OM and OI exhibited a more pronounced loss of MVC in the lower limb [OM (-60%) and OI (-75%)] than the upper limb (OM = -51%; OI = -47%). Taking into account the reduction in muscle PCSA (OM = -10%; OI = -18%), only evident in the lower limb, by calculating voluntary muscle-specific force, the lower limb of the OI (-40%) was more compromised than the OM (-13%). However, in vivo, RT in both upper and lower limbs (approx. 9.8 N m cm(-2) ) and Po (approx. 123 mN mm(-2) ), assessed in vitro, implies preserved intrinsic contractile function in all muscles of the oldest-old and were well correlated (r = 0.81). CONCLUSION These findings suggest that in the oldest-old, neither advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function, as assessed in vitro. However, in vivo, muscle function is attenuated by age and exacerbated by disuse, implicating factors other than skeletal muscle, such as neuromuscular control, in this diminution of function.
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Affiliation(s)
- M. Venturelli
- Department of Biomedical Sciences for Health; University of Milan; Milan Italy
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - P. Saggin
- Division of Radiology and Imaging; City of Verona Diagnostic Center; Verona Italy
| | - E. Muti
- Mons. Mazzali Foundation; Mantova Italy
| | - F. Naro
- DAHFMO Unit of Histology and Medical Embryology; Sapienza University; Rome Italy
| | - L. Cancellara
- Department of Biomedical Sciences; University of Padova; Padova Italy
| | - L. Toniolo
- Department of Biomedical Sciences; University of Padova; Padova Italy
| | - C. Tarperi
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - E. Calabria
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - R. S. Richardson
- Division of Geriatrics; Department of Internal Medicine; University of Utah School of Medicine; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Wahlen Department of Veterans Affairs Medical Center; Salt Lake City UT USA
- Department of Exercise and Sport Science; University of Utah; Salt Lake City UT USA
| | - C. Reggiani
- Department of Biomedical Sciences; University of Padova; Padova Italy
- CNR (Consiglio Nazionale delle Ricerche); Institute of Neuroscience; Padua Italy
| | - F. Schena
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
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Mänttäri S, Ørtenblad N, Madsen K, Pilegaard H. Both short intense and prolonged moderate in vitro stimulation reduce the mRNA expression of calcium-regulatory proteins in rat skeletal muscle. Mol Cell Biochem 2012; 373:171-8. [DOI: 10.1007/s11010-012-1486-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
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Hilber K. Skeletal myocyte plasticity: basis for improved therapeutic potential? Curr Opin Pharmacol 2008; 8:327-32. [PMID: 18329336 DOI: 10.1016/j.coph.2008.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/18/2008] [Accepted: 01/25/2008] [Indexed: 12/25/2022]
Abstract
Skeletal muscle tissue exhibits a remarkable capacity to regenerate after injury and to adapt its properties in response to altered functional demands or environmental pressure. This potential renders skeletal myocytes especially attractive candidates to be used in therapeutic strategies. Besides the well-described adaptability of skeletal myocytes in terms of contractile function and metabolic profile, more recent research has revealed that the electrophysiological properties of myocytes are also subject to significant changes both under physiological conditions and in pathophysiological situations. A better understanding of skeletal myocyte plasticity, its regulation and its forced induction could improve existing therapeutic approaches and may pave the way for new therapeutic strategies.
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Affiliation(s)
- Karlheinz Hilber
- Center of Biomolecular Medicine and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13A, 1090 Vienna, Austria.
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Mänttiri S, Anttila K, Kaakinen M, Järvilehto M. Effects of low-intensity training on dihydropyridine and ryanodine receptor content in skeletal muscle of mouse. J Physiol Biochem 2007; 62:293-301. [PMID: 17615955 DOI: 10.1007/bf03165758] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To evaluate low-intensity exercise training induced changes in the expression of dihydropyridine (DHP) and ryanodine (Ry) receptors both mRNA and protein levels were determined by quantitative RT-PCR and immunoblot analysis from gastrocnemius (GAS) and rectus femoris (RF) muscles of mice subjected to a 15-week aerobic exercise program. The level of muscular work was assayed by changes in myosin heavy chain (MHC) content, myoglobin (Mb) expression and muscle size. The mRNA expression and optical density of DHP receptor increased significantly in GAS by 66.8 and 39.5%, respectively. The expression of Ry receptor, on the other hand, was not up-regulated. In RF, there was a significant increase of 38.4% in the mRNA expression of DHP receptor, although the protein level remained the same. No changes in Ry receptor expression was observed. The training resulted in a 1.58% increase in the amount of MHC IIa and a 2.34% decrease in that of IIb and IId in GAS. A significant 8.3% increase in the Mb content was observed. In RF, no significant changes in MHC or in Mb content were noted. Our results show that an evident increase in the mRNA and protein expression of DHP receptor was induced in GAS even by a relatively low-intensity exercise. Surprisingly, contrast to DHP receptor expression, no changes in Ry receptor mRNA, or protein levels were found, indicating more abundant demand for DHP receptor after increased muscle activity.
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Affiliation(s)
- S Mänttiri
- Department of Biology, Animal Physiology, University of Oulu, Finland.
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5
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Anttila K, Mänttäri S, Järvilehto M. Expression of dihydropyridine and ryanodine receptors in type IIA fibers of rat skeletal muscle. Acta Histochem Cytochem 2007; 40:35-41. [PMID: 17576431 PMCID: PMC1874508 DOI: 10.1267/ahc.06028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Accepted: 02/07/2007] [Indexed: 01/07/2023] Open
Abstract
In this study, the fiber type specificity of dihydropyridine receptors (DHPRs) and ryanodine receptors (RyRs) in different rat limb muscles was investigated. Western blot and histochemical analyses provided for the first time evidence that the expression of both receptors correlates to a specific myosin heavy chain (MHC) composition. We observed a significant (p=0.01) correlation between DHP as well as Ry receptor density and the expression of MHC IIa (correlation factor r=0.674 and r=0.645, respectively) in one slow-twitch, postural muscle (m. soleus), one mixed, fast-twitch muscle (m. gastrocnemius) and two fast-twitch muscles (m. rectus femoris, m. extensor digitorum longus). The highest DHP and Ry receptor density was found in the white part of m. rectus femoris (0.058+/-0.0060 and 0.057+/-0.0158 ODu, respectively). As expected, the highest relative percentage of MHC IIa was also found in the white part of m. rectus femoris (70.0+/-7.77%). Furthermore, histochemical experiments revealed that the IIA fibers stained most strongly for the fluorophore-conjugated receptor blockers. Our data clearly suggest that the expression of DHPRs and RyRs follows a fiber type-specific pattern, indicating an important role for these proteins in the maintenance of an effective Ca2+ cycle in the fast contracting fiber type IIA.
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Affiliation(s)
- Katja Anttila
- Department of Biology, University of Oulu, P. O. Box 3000, FIN-90014 Oulun yliopisto, Finland
| | - Satu Mänttäri
- Department of Biology, University of Oulu, P. O. Box 3000, FIN-90014 Oulun yliopisto, Finland
| | - Matti Järvilehto
- Department of Biology, University of Oulu, P. O. Box 3000, FIN-90014 Oulun yliopisto, Finland
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Esposito A, Germinario E, Zanin M, Palade PT, Betto R, Danieli-Betto D. Isoform switching in myofibrillar and excitation-contraction coupling proteins contributes to diminished contractile function in regenerating rat soleus muscle. J Appl Physiol (1985) 2007; 102:1640-8. [PMID: 17234797 DOI: 10.1152/japplphysiol.01397.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Postnatal development of skeletal muscle occurs through the progressive transformation of diverse biochemical, metabolic, morphological, and functional characteristics from the embryonic to the adult phenotype. Since muscle regeneration recapitulates postnatal development of muscle fiber, it offers an appropriate experimental model to investigate the existing relationships between diverse muscle functions and the expression of key protein isoforms, particularly at the single-fiber level. This study was carried out in regenerating soleus muscle 14 days after injury. At this intermediate stage, the regenerating muscle exhibited a recovery of mass greater than its force generation capacity. The lower specific tension of regenerating muscle suggested intrinsic defective excitation-contraction coupling and/or contractility processes. The presence of developmental isoforms of both the voltage-gated Ca2+channel (α1C) and of ryanodine receptor 3, paralleled by an abnormal caffeine contracture development, confirms the immature excitation-contraction coupling of the regenerating muscle. The defective Ca2+handling could also be confirmed by the lower sarcoplasmic reticulum caffeine sensitivity of regenerating single fibers. Also, regenerating single fibers revealed a lower maximal specific tension, which was associated with the residual presence of embryonic myosin heavy chains. Moreover, the fibers showed a reduced Ca2+sensitivity of myofibrillar proteins, particularly those simultaneously expressing the slow and fast isoforms of troponin C. The present results indicate that the expression of developmental proteins determines the incomplete functional recovery of regenerating soleus.
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Affiliation(s)
- Alessandra Esposito
- Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
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Reggiani C, te Kronnie T. RyR isoforms and fibre type-specific expression of proteins controlling intracellular calcium concentration in skeletal muscles. J Muscle Res Cell Motil 2006; 27:327-35. [PMID: 16874451 DOI: 10.1007/s10974-006-9076-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Accepted: 06/21/2006] [Indexed: 11/28/2022]
Abstract
Muscle fibres which shorten with high maximum shortening velocity also exhibit fast kinetics of contraction, i.e. short values of time to peak tension and time to half relaxation. This short review aims to discuss the molecular basis of such correlation, to reach, based on the available literature, an answer to the question whether there is a correlation in expression of proteins determining shortening velocity, myosin isoforms in the first place, and proteins controlling cytosolic calcium concentration and its variations at rest or during contraction. Although the isoforms of RyR, the sarcoplasmic calcium release channels, do not show a tightly coordinated expression with myosin isoforms, other proteins involved in controlling intracellular calcium do. This is likely sufficient to guarantee the correlation between maximum shortening velocity and speed of isometric contraction.
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Affiliation(s)
- Carlo Reggiani
- Department of Anatomy and Physiology, University of Padova, Via Marzolo 3, 35131, Padova, Italy.
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Saada NI, Carrillo ED, Dai B, Wang WZ, Dettbarn C, Sanchez J, Palade P. Expression of multiple CaV1.2 transcripts in rat tissues mediated by different promoters. Cell Calcium 2005; 37:301-9. [PMID: 15755491 DOI: 10.1016/j.ceca.2004.11.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 11/05/2004] [Accepted: 11/05/2004] [Indexed: 10/25/2022]
Abstract
The expression of two different transcripts for Ca(V)1.2 in rat tissues mirrors that which has previously been described for human tissue, in that expression of transcripts expressing exon 1a is predominant only in heart, whereas expression of transcripts expressing exon 1b is greater in smooth muscle rich tissues such as aorta and intestine. Transcripts expressing exon 1b also predominate in brain and in diaphragm. Western blots indicate that the N-terminus coded for by exon 1b is present in much of the protein in all these tissues except heart. The promoter just upstream of exon 1b has been cloned, sequenced and utilized to drive expression of luciferase in smooth muscle A7r5 cells, cardiac HL-1 cells, skeletal muscle L6 cells and neuronal PC12 cells. The nucleotide sequence of the promoter exhibits 80% identity with the equivalent promoter previously identified in humans and 94% identity with the sequence of the equivalent region of the mouse genome. Evidence in favor of still another promoter upstream of exon 2 has been uncovered.
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Affiliation(s)
- Nehad I Saada
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-0641, USA
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Radzyukevich TL, Heiny JA. Regulation of dihydropyridine receptor gene expression in mouse skeletal muscles by stretch and disuse. Am J Physiol Cell Physiol 2004; 287:C1445-52. [PMID: 15294855 DOI: 10.1152/ajpcell.00518.2003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examined dihydropyridine receptor (DHPR) gene expression in mouse skeletal muscles during physiological adaptations to disuse. Disuse was produced by three in vivo models-denervation, tenotomy, and immobilization-and DHPR alpha1s mRNA was measured by quantitative Northern blot. After 14-day simultaneous denervation of the soleus (Sol), tibialis anterior (TA), extensor digitorum longus (EDL), and gastrocnemius (Gastr) muscles by sciatic nerve section, DHPR mRNA increased preferentially in the Sol and TA (+1.6-fold), whereas it increased in the EDL (+1.6-fold) and TA (+1.8-fold) after selective denervation of these muscles by peroneal nerve section. It declined in all muscles (-1.3- to -2.6-fold) after 14-day tenotomy, which preserves nerve input but removes mechanical tension. Atrophy was comparable in denervated and tenotomized muscles. These results suggest that factor(s) in addition to inactivity per se, muscle phenotype, or associated atrophy can regulate DHPR gene expression. To test the contribution of passive tension to this regulation, we subjected the same muscles to disuse by limb immobilization in a maximally dorsiflexed position. DHPR alpha1s mRNA increased in the stretched muscles (Sol, +2.3-fold; Gastr, +1.5-fold) and decreased in the shortened muscles (TA, -1.4-fold; EDL, -1.3-fold). The effect of stretch was confirmed in vitro. DHPR protein did not change significantly after 4-day immobilization, suggesting that additional levels of regulation may exist. These results demonstrate that DHPR alpha1s gene expression is regulated as an integral part of the adaptive response of skeletal muscles to disuse in both slow- and fast-twitch muscles and identify passive tension as an important signal for its regulation in vivo.
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Affiliation(s)
- Tatiana L Radzyukevich
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio 45267-0576, USA
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10
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Abstract
Functional and structural decline in the neuromuscular system with aging has been recognized as a cause of impairment in physical performance and loss of independence in the elderly. Alterations in spinal cord motor neurones and at the neuromuscular junction have been identified as evidence of denervation in skeletal muscles from aging mammals, including humans. However, the reciprocal influences of neurones on gene expression in muscle and of muscle on age-related neurodegeneration are poorly understood, and, as a result, interventions aimed at delaying or preventing degeneration of the neural component in aging muscle have been largely unsuccessful. The present article discusses the evidence for neural influence on age-related impairments of skeletal muscle, including a role in excitation-contraction uncoupling. The role of nerves in regulating the trophic actions of insulin-like growth factor-1 (IGF-1) and other neurotrophic factors is considered as a novel influence on the effects of aging on the neuromuscular junction. A better understanding of nerve-muscle interactions will allow for more rational interventions in the aging neuromuscular system.
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Affiliation(s)
- Osvaldo Delbono
- Department of Physiology and Pharmacology, Neuroscience Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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Froemming GR, Murray BE, Harmon S, Pette D, Ohlendieck K. Comparative analysis of the isoform expression pattern of Ca(2+)-regulatory membrane proteins in fast-twitch, slow-twitch, cardiac, neonatal and chronic low-frequency stimulated muscle fibers. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1466:151-68. [PMID: 10825439 DOI: 10.1016/s0005-2736(00)00195-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although all muscle cells generate contractile forces by means of organized filament systems, isoform expression patterns of contractile and regulatory proteins in heart are not identical compared to developing, conditioned or mature skeletal muscles. In order to determine biochemical parameters that may reflect functional variations in the Ca(2+)-regulatory membrane systems of different muscle types, we performed a comparative immunoblot analysis of key membrane proteins involved in ion homeostasis. Cardiac isoforms of the alpha(1)-dihydropyridine receptor, Ca(2+)-ATPase and calsequestrin are also present in skeletal muscle and are up-regulated in chronic low-frequency stimulated fast muscle. In contrast, the cardiac RyR2 isoform of the Ca(2+)-release channel was not found in slow muscle but was detectable in neonatal skeletal muscle. Up-regulation of RyR2 in conditioned muscle was probably due to degeneration-regeneration processes. Fiber type-specific differences were also detected in the abundance of auxiliary subunits of the dihydropyridine receptor, the ryanodine receptor and the Ca(2+)-ATPase, as well as triad markers and various Ca(2+)-binding and ion-regulatory proteins. Hence, the variation in innervation of different types of muscle appears to have a profound influence on the levels and pattern of isoform expression of Ca(2+)-regulatory membrane proteins reflecting differences in the regulation of Ca(2+)-homeostasis. However, independent of the muscle cell type, key Ca(2+)-regulatory proteins exist as oligomeric complexes under native conditions.
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Affiliation(s)
- G R Froemming
- Department of Pharmacology, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Pääsuke M, Ereline J, Gapeyeva H. Neuromuscular fatigue during repeated exhaustive submaximal static contractions of knee extensor muscles in endurance-trained, power-trained and untrained men. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 166:319-26. [PMID: 10468669 DOI: 10.1046/j.1365-201x.1999.00573.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The neural and muscular changes during fatigue produced in repeated submaximal static contractions of knee extensors were measured. Three groups of differently adapted male subjects (power-trained, endurance-trained and untrained, 15 in each) performed the exercise that consisted of 10 trials of submaximal static contractions at the level of 40% of maximal voluntary contraction (MVC) force till exhaustion with the inter-trial rest intervals of 1 min. MVC force, reaction time and patellar reflex time components before and after the fatiguing exercise and following 5, 10 and 15 min of recovery were recorded. Endurance-trained athletes had a significantly longer holding times for all the 10 trials compared with power-trained athletes and untrained subjects. However, no significant differences in static endurance between power-trained athletes and untrained subjects were noted. The fatigue test significantly prolonged the time between onset of electrical and mechanical activity (electromechanical delay) in voluntary and reflex contractions. The electromechanical delay in voluntary contraction condition for power-trained and untrained subjects and in reflex condition for endurance-trained subjects had not recovered 15 min after cessation of exercise. No significant changes in the central component of visual reaction time (premotor time of MVC) and latency of patellar reflex were noted after fatiguing static exercise. It is concluded, that in this type of exercise the fatigue development may be largely owing to muscle contractile failure.
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Affiliation(s)
- M Pääsuke
- University of Tartu, Institute of Exercise Biology, Tartu, Estonia
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Abstract
The model of chronic low-frequency stimulation for the study of muscle plasticity was developed over 30 years ago. This protocol leads to a transformation of fast, fatigable muscles toward slower, fatigue-resistant ones. It involves qualitative and quantitative changes of all elements of the muscle fiber studied so far. The multitude of stimulation-induced changes makes it possible to establish the full adaptive potential of skeletal muscle. Both functional and structural alterations are caused by orchestrated exchanges of fast protein isoforms with their slow counterparts, as well as by altered levels of expression. This remodeling of the muscle fiber encompasses the major, myofibrillar proteins, membrane-bound and soluble proteins involved in Ca2+ dynamics, and mitochondrial and cytosolic enzymes of energy metabolism. Most transitions occur in a coordinated, time-dependent manner and result from altered gene expression, including transcriptional and posttranscriptional processes. This review summarizes the advantages of chronic low-frequency stimulation for studying activity-induced changes in phenotype, and its potential for investigating regulatory mechanisms of gene expression. The potential clinical relevance or utility of the technique is also considered.
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Affiliation(s)
- D Pette
- Faculty of Biology, University of Konstanz, Germany
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Péréon Y, Dettbarn C, Navarro J, Noireaud J, Palade PT. Dihydropyridine receptor gene expression in skeletal muscle from mdx and control mice. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1362:201-7. [PMID: 9540851 DOI: 10.1016/s0925-4439(97)00079-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The expression of isoform-specific dihydropyrine receptor-calcium channel (DHPR) alpha 1-subunit genes was investigated in mdx and control mouse diaphragm (DIA) and tibialis anterior (TA). RNase protection assays were carried out with a rat DHPR cDNA probe specific for skeletal muscle and a mouse DHPR cDNA probe specific for cardiac muscle. The level of expression of the gene encoding the cardiac DHPR was very weak in TA muscle from both control and mdx mice. Compared to TA, DIA expressed mRNA for the cardiac isoform at significantly higher levels, but mdx and control mouse DIA levels were similar to one another. In contrast, mRNA expression levels for the DHPR skeletal muscle isoform were lower in control DIA than TA. However, there was a dramatic increase in the expression for the DHPR skeletal muscle isoform in mdx DIA compared with control DIA, reaching the TA expression level, whereas dystrophy did not affect TA expression. [3H]-PN200-110 binding was used to further assess DIA DHPR expression at the protein level. The density of binding sites for the probe was not significantly affected in DIA muscles of mdx vs. control mice, but it was reduced in older mdx and control mice. The increase in DHPR mRNA levels without a consequent increase in DHPR protein expression could be secondary to possible enhanced protein degradation which occurs in mdx DIA. The altered DHPR expression levels found here do not appear to be responsible for the severe deficits in contractile function of the mdx DIA.
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Affiliation(s)
- Y Péréon
- Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555-0641, USA
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Péréon Y, Sorrentino V, Dettbarn C, Noireaud J, Palade P. Dihydropyridine receptor and ryanodine receptor gene expression in long-term denervated rat muscles. Biochem Biophys Res Commun 1997; 240:612-7. [PMID: 9398613 DOI: 10.1006/bbrc.1997.7712] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Following disruption of the nerve supply, extensor digitorum longus (EDL) and soleus (SOL) muscles in rats are known to exhibit alterations in excitation-contraction coupling. After total RNA isolation from the denervated and the contralateral control muscles performed at 25 and 50 days following denervation, RNase protection assays were carried out with four cDNA probes specific for the skeletal and cardiac isoforms of both the DHPR alpha 1-subunit and the RyR. Longterm denervation increased the expression of the mRNA for skeletal DHPR and skeletal RyR in SOL muscle, but it also significantly increased the expression of the mRNA for the cardiac isoform of the DHPR alpha 1 subunit in EDL muscle.
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Affiliation(s)
- Y Péréon
- Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555-0641, USA.
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