Mechanisms of fatigue in normal intercostal muscle and muscle from patients with myasthenia gravis
| Autor: | Murali Pagala, N. V. Nandakumar, Kadirimangalam Ravindran, Tatsuji Namba, Bellamakonda Amaladevi, S. A. T. Venkatachari, David Grob |
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| Rok vydání: | 1993 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Physiology Neuromuscular transmission Action Potentials Intercostal Muscles Electromyography In Vitro Techniques Nervous System Contractility Cellular and Molecular Neuroscience Physiology (medical) Internal medicine Myasthenia Gravis Medicine Humans Fatigue medicine.diagnostic_test Muscle fatigue business.industry Anatomy Middle Aged medicine.disease Myasthenia gravis Electric Stimulation Compound muscle action potential Endocrinology medicine.anatomical_structure Female Neurology (clinical) Muscle Stimulation business Intercostal muscle Muscle Contraction |
| Zdroj: | Musclenerve. 16(9) |
| ISSN: | 0148-639X |
| Popis: | Fatigue mechanisms in normal intercostal muscle and muscle from patients with myasthenia gravis (MG) were evaluated by monitoring the compound muscle action potential (CMAP) and tetanic tension responses to repetitive nerve or muscle stimulation in vitro. When fatigue was induced by nerve stimulation at 30 Hz for 0.5 s every 2.5 s, about half of the original tension decreased after 30 min in normal muscle and 5 min in MG muscle. Analysis of the changes in area of CMAPs and tension indicated that impairment of neuromuscular transmission, muscle membrane excitation, and excitation-contraction (E-C) coupling and contractility accounted for 40%, 29%, and 31% of fatigue in normal muscle, and 83%, 0%, and 17% of fatigue in MG muscle. When fatigue was induced by muscle stimulation at 30 Hz, tension declined by a quarter after 30 min in normal muscle, but by a half after 17 min in MG muscle. Impairment of muscle membrane excitation and E-C coupling and contractility accounted for 58% and 42% of fatigue in normal muscle, and 22% and 78% of fatigue in MG muscle. Thus, fatigue of normal muscle is caused by impairment of at least four processes, and enhanced fatigue of MG muscle is caused by greater impairment of neuromuscular transmission, E-C coupling, and contractility. © 1993 John Wiley & Sons, Inc. |
| Databáze: | OpenAIRE |
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