caa a22 4500 475744993 CHVBK 20180406123510.0 cr unu---uuuuu 170329e20000401xx s 000 0 eng 10.1023/A:1005676312176 doi (NATIONALLICENCE)springer-10.1023/A:1005676312176 Effect of tibial bone resection on the development of fast- and slow-twitch skeletal muscles in foetal sheep [Elektronische Daten] [Jan West, Natalie Williams, Anthony Luff, David Walker] To determine if longitudinal bone growth affects the differentiation of fast- and slow-twitch muscles, the tibial bone was sectioned at 90 days gestation in foetal sheep so that the lower leg was permanently without structural support. At 140 days (term is ∼147 days) the contractile properties of whole muscles, activation profiles of single fibres and ultrastructure of fast- and slow-twitch muscles from the hindlimbs were studied. The contractile and activation profiles of the slow-twitch soleus muscles were significantly affected by tibial bone resection (TIBX). The soleus muscles from the TIBX hindlimbs showed: (1) a decrease in the time to peak of the twitch responses from 106.2 ± 10.7 ms (control, n = 4) to 65.1 ± 2.48 ms (TIBX, n = 5); (2) fatigue profiles more characteristic of those observed in the fast-twitch muscles; and (3) Ca2+- and Sr2+-activation profiles of skinned fibres similar to those from intact hindlimbs at earlier stages of gestation. In the FDL, TIBX did not significantly change whole muscle twitch contraction time, the fatigue profile or the Ca2+- and Sr2+-activation profiles of skinned fibres. Electron microscopy showed an increased deposition of glycogen in both soleus and FDL muscles. This study shows that the development of the slow-twitch phenotype is impeded in the absence of the physical support normally provided by the tibial bone. We suggest that longitudinal stretch is an important factor in allowing full expression of the slow-twitch phenotype. Kluwer Academic Publishers, 2000 West Jan Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut Williams Natalie School of Human Movement Studies, Queensland University of Technology, Victoria Park Road, 4059, Kelvin Grove, Queensland, Australia aut Luff Anthony Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut Walker David Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/3(2000-04-01), 209-222 0142-4319 21:3<209 2000 21 10974 https://doi.org/10.1023/A:1005676312176 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005676312176 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- West Jan Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut NATIONALLICENCE 700 1- Williams Natalie School of Human Movement Studies, Queensland University of Technology, Victoria Park Road, 4059, Kelvin Grove, Queensland, Australia aut NATIONALLICENCE 700 1- Luff Anthony Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut NATIONALLICENCE 700 1- Walker David Department of Physiology, Monash University, 3800, Clayton, Victoria, Australia aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/3(2000-04-01), 209-222 0142-4319 21:3<209 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer