Biomédico

Physiol Rev 91: 1447–1531, 2011 doi:10.1152/physrev.00031.2010

FIBER TYPES IN MAMMALIAN SKELETAL MUSCLES
Stefano Schiaffino and Carlo Reggiani
Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy

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Schiaffino S, Reggiani C. Fiber Types In Mammalian Skeletal Muscles. Physiol Rev 91: 1447–1531, 2011; doi:10.1152/physrev.00031.2010.—Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
INTRODUCTION FIBER TYPE HETEROGENEITY IN... MUSCLE FIBER DIVERSITY IN... VARIATIONS