Effects of bedrest on deltoideus muscle morphology and enzymes
Abstract:To examine the effects of unweighting on the structural and metabolic adaptations of a non-postural muscle, deltoideus muscle biopsies were taken in seven male healthy subjects, before and after a 37 day bedrest. Myofibrillar ATPase histochemistry demonstrated no change in fibre type distributions (I, IIA, IIB), in fibre cross-sectional areas nor in capillary supply. No difference was noted in enzyme activities of oxidative metabolism (citrate synthase, 3-hydroxy-acyl-CoA dehydrogenase), and glycolysis (hexokinase, lactate dehydrogenase). Electron microscopy showed a decrease in the volume density of lipids but no change in mitochondrial volume density and distribution. The results indicate that bedrest induces no major morphological and biochemical changes in deltoideus muscle, contrary to what was previously reported in vastus lateralis muscle. This lack of changes is probably related to an unaltered deltoideus muscle use.
Document Type: Original Article
Affiliations: 1: UMR 5578 CNRS, Laboratoire de Physiologie, Université Lyon I, F-69373 Lyon Cedex 08, France 2: Anatomisches Institut, Universitt Bern, CH-3000 Bern, Switzerland 3: Laboratoire de Physiologie-G.I.P. Exercice, Faculté de Médecine, F-42023 St Etienne Cedex 2, France 4: Departement de Physiology, Centre Médical Universitaire, 1211 Geneva 4, Switzerland
Publication date: February 1, 1998