J H Williams1. 1. Muscular Function Laboratory, Department of Human Nutrition, Foods and Exercise, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
Abstract
AIMS: Fatigue has been shown to cause intrinsic alterations in sarcoplasmic reticulum (SR) Ca2+ release. METHODS: In this investigation, frog semitendinosus muscles were stimulated to fatigue, in vitro (80 Hz, 100 ms, 1 train s-1, 5 min). Immediately after stimulation, single fibres were removed and skinned using either chemically or mechanically skinning. Contralateral muscle were treated similarly but were not stimulated. RESULTS: In fatigued, saponin skinned fibres, contracture responses to low [caffeine] (4-8 mm) were depressed compared with control. However, responses to high concentrations (10-15 mm) were not different between conditions. In the fatigued, mechanically skinned fibres, responses to chloride depolarization were depressed at all [chloride] (20-100 mm) compared with control. CONCLUSIONS: These results suggest that fatigue causes intrinsic alterations in both the SR Ca2+ release channel as well as communication between the transverse-tubule and the SR.
AIMS: Fatigue has been shown to cause intrinsic alterations in sarcoplasmic reticulum (SR) Ca2+ release. METHODS: In this investigation, frog semitendinosus muscles were stimulated to fatigue, in vitro (80 Hz, 100 ms, 1 train s-1, 5 min). Immediately after stimulation, single fibres were removed and skinned using either chemically or mechanically skinning. Contralateral muscle were treated similarly but were not stimulated. RESULTS: In fatigued, saponin skinned fibres, contracture responses to low [caffeine] (4-8 mm) were depressed compared with control. However, responses to high concentrations (10-15 mm) were not different between conditions. In the fatigued, mechanically skinned fibres, responses to chloride depolarization were depressed at all [chloride] (20-100 mm) compared with control. CONCLUSIONS: These results suggest that fatigue causes intrinsic alterations in both the SR Ca2+ release channel as well as communication between the transverse-tubule and the SR.
Authors: Juliet A Usher-Smith; James A Fraser; Christopher L-H Huang; Jeremy N Skepper Journal: J Muscle Res Cell Motil Date: 2007-03-02 Impact factor: 2.698