........................................................................................................................................ ii ABBREVIATIONS ............................................................................................................................ iii ACKNOWLEDGEMENTS .................................................................................................................. v TABLE OF CONTENTS.................................................................................................................... vi TABLE OF FIGURES ...................................................................................................................... viii LIST OF TABLES ................................................................................................................................ x INTRODUCTION ............................................................................................................................... 1 Muscle contraction ..................................................................................................................... 3 Fatigue ............................................................................................................................................ 5 Energy balance: ‘raison d’être’ of muscle fatigue ..................................................................... 5 Role of metabolites in the decrease in force during fatigue at the sarcomere level ... 7 Fatigue involves a decrease of Ca2+ release by SR .................................................................... 8 Membrane excitability and fatigue .............................................................................................. 11 KATP channel ................................................................................................................................ 12 KATP channel molecular structure ................................................................................................ 13 Regulation of KATP channel activity ............................................................................................. 15 Physiological roles of KATP channel ............................................................................................. 17 Myoprotection ....................................................................................................................................................................... 17 NAC also abolishes resting tension in KATP -/muscle .......................................................... 20 Objective and hypothesis ....................................................................................................... 21 METHODS AND MATERIALS ...................................................................................................... 23 Animals and KATP channel deficient muscle fibres........................................................ 23 Single fibre preparation ......................................................................................................... 23 Experimental setup & solutions .......................................................................................... 24 Fibre stimulation ...................................................................................................................... 25 [Ca2+]i measurement ................................................................................................................ 25 Sarcomere length measurement ......................................................................................... 26 Experimental protocol ............................................................................................................ 28 Statistical analysis .................................................................................................................... 28 RESULTS ........................................................................................................................................... 29 Isolation of viable single fibres ............................................................................................ 29 Importance of FBS during the collagenase digestion ........................................................... 29 Importance of culture medium and FBS in the physiological solution ......................... 31