Spastic muscle cells are shorter and stiffer than normal cells

The mechanical properties of isolated single muscle fiber segments were measured in muscle cells obtained from patients undergoing surgery for correction of flexion contractures secondary to static perinatal encephalopathy (cerebral palsy). “Normal” muscle cells from patients with intact neuromuscular function were also mechanically tested. Fiber segments taken from subjects with spasticity developed passive tension at significantly shorter sarcomere lengths (1.84 ± 0.05 μm, n = 15) than fibers taken from normal subjects (2.20 ± 0.04 μm, n = 35). Elastic modulus of the stress–strain relationship in fibers from patients with spasticity (55.00 ± 6.61 kPa) was almost double that measured in normal fibers (28.25 ± 3.31 kPa). The fact that these muscle cells from patients with spasticity have a shorter resting sarcomere length and increased modulus compared with normal muscle cells suggests dramatic remodeling of intracellular or extracellular muscle structural components such as titin and collagen. Such changes in muscles of patients with spasticity may have implications for therapy. Muscle Nerve, 27: 157–164 ,2003

[1]  R. J. Podolsky,et al.  Force measurements in skinned muscle fibres , 1969, The Journal of physiology.

[2]  W. Peacock,et al.  The surgical treatment of spasticity , 2000, Muscle & nerve.

[3]  C. Tardieu,et al.  Muscle hypoextensibility in children with cerebral palsy: II. Therapeutic implications. , 1982, Archives of physical medicine and rehabilitation.

[4]  R. Baskin,et al.  Sarcomere length determination using laser diffraction. Effect of beam and fiber diameter. , 1984, Biophysical journal.

[5]  J. Trotter,et al.  Functional morphology of the endomysium in series fibered muscles , 1992, Journal of morphology.

[6]  M. Reedy,et al.  X-ray diffraction observations of chemically skinned frog skeletal muscle processed by an improved method. , 1980, Biophysical journal.

[7]  T Sinkjaer,et al.  Passive, intrinsic and reflex-mediated stiffness in the ankle extensors of hemiparetic patients. , 1994, Brain : a journal of neurology.

[8]  L. Leinwand,et al.  Comparative sequence analysis of the complete human sarcomeric myosin heavy chain family: implications for functional diversity. , 1999, Journal of molecular biology.

[9]  S. Andreassen,et al.  Non–reflex and reflex mediated ankle joint stiffness in multiple sclerosis patients with spasticity , 1993, Muscle & nerve.

[10]  D. S. Wood,et al.  Human Skeletal Muscle: Properties of the "Chemically Skinned%" Fiber , 1975, Science.

[11]  R. Baskin,et al.  Light diffraction study of single skeletal muscle fibres. , 1979, Biophysical journal.

[12]  G. Vrbóva,et al.  Invited review: Neural control of phenotypic expression in mammalian muscle fibers , 1985, Muscle & nerve.

[13]  Peter P. Purslow,et al.  The morphology and mechanical properties of endomysium in series-fibred muscles: variations with muscle length , 1994, Journal of Muscle Research & Cell Motility.

[14]  J. Rose,et al.  Muscle pathology and clinical measures of disability in children with cerebral palsy , 1994, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[15]  R R Roy,et al.  Electrophoretic separation of rat skeletal muscle myosin heavy-chain isoforms. , 1993, Journal of applied physiology.

[16]  Siegfried Labeit,et al.  Titins: Giant Proteins in Charge of Muscle Ultrastructure and Elasticity , 1995, Science.

[17]  E. Kempner,et al.  A physiological role for titin and nebulin in skeletal muscle , 1986, Nature.

[18]  R. Lieber,et al.  Four novel myosin heavy chain transcripts define a molecular basis for muscle fibre types in Ranapipiens , 1998, The Journal of physiology.

[19]  R. Kearney,et al.  Intrinsic and reflex stiffness in normal and spastic, spinal cord injured subjects , 2001, Experimental Brain Research.

[20]  W. Rymer,et al.  Spastic hypertonia: mechanisms and measurement. , 1989, Archives of physical medicine and rehabilitation.

[21]  C Tardieu,et al.  Muscle hypoextensibility in children with cerebral palsy: I. Clinical and experimental observations. , 1982, Archives of physical medicine and rehabilitation.

[22]  J Quintern,et al.  Electrophysiological studies of gait in spasticity and rigidity. Evidence that altered mechanical properties of muscle contribute to hypertonia. , 1981, Brain : a journal of neurology.

[23]  M. Keenan.  The orthopedic management of spasticity , 1987 .

[24]  F. Booth.  Effect of limb immobilization on skeletal muscle. , 1982, Journal of applied physiology: respiratory, environmental and exercise physiology.

[25]  R. Lieber,et al.  Architecture of selected wrist flexor and extensor muscles. , 1990, The Journal of hand surgery.

[26]  A. Magid,et al.  Myofibrils bear most of the resting tension in frog skeletal muscle. , 1985, Science.

[27]  Richard L Lieber,et al.  Spasticity causes a fundamental rearrangement of muscle–joint interaction , 2002, Muscle & nerve.

[28]  L. Leinwand,et al.  Type IIx myosin heavy chain transcripts are expressed in type IIb fibers of human skeletal muscle. , 1994, The American journal of physiology.

[29]  R. Moss.  Sarcomere length‐tension relations of frog skinned muscle fibres during calcium activation at short lengths. , 1979, The Journal of physiology.