Muscle Biophysics (eBook)

Muscle Biophysics 3
Copyright 4
Preface 5
References 6
Contents 9
Contributors 11
Striated Muscles: From Molecules to Cells 15
1 Striated Muscle Organization 15
1.1 Single Muscle Fibers 16
1.2 Single Myofibrils and Sarcomeres 17
1.3 Single Filaments and Molecules 18
References 20
Contractile Performance of Striated Muscle 21
1 Introduction 21
2 The Length–Tension Relationship in Striated Muscle 23
3 The Force–Velocity Relationship. Maximum Velocity of Shortening 26
4 The Slack Test Method. Braking Force of Cross-Bridges at Negative Strain 31
5 Force Enhancement by Stretch 33
5.1 Force Enhancement During Stretch, Its Relation to Sarcomere Length and Myofilament Lattice Width 34
5.2 Residual Force Enhancement After Stretch 37
6 Force Reduction After Loaded Shortening 39
7 Deactivation by Active Shortening 41
8 Differences in Kinetic Properties Along Individual Muscle Fibers 48
References 51
Energy Economy in the Actomyosin Interaction: Lessons from Simple Models 55
1 Introduction 55
2 Lessons from a Two State Model 57
3 Lessons from a Three State Model 62
4 Conclusions and Future Directions 66
References 67
A Strain-Dependency of Myosin Off-Rate Must Be Sensitive to Frequency to Predict the B-Process of Sinusoidal Analysis 70
1 Introduction 71
2 Small Sinusoidal Length Perturbation Analysis 72
3 Analytical Results 76
3.1 ODE Solution for Isometric Force and C-Process 77
3.2 Simple Strain Dependency on Myosin Off-Rate 81
3.3 A Frequency Dependency on the Strain-Dependence of Myosin Off-Rate 82
4 Discussion 85
References 86
Electron Microscopic Visualization of the Cross-Bridge Movement Coupled with ATP Hydrolysis in Muscle Thick Filaments in Aque 89
1 Introduction 89
2 The EC System 91
2.1 Carbon Sealing Film 91
2.2 The EC 91
3 Observation and Recording of Specimen Image 93
3.1 The Critical Incident Electron Dose to Impair Function of Contractile Proteins 93
3.2 Recording of Specimen Image 94
3.3 Application of ATP and ADP 95
3.4 Position Marking of Individual Cross-Bridges 95
3.5 Data Analysis 96
4 Experiments with Myosin–Paramyosin Hybrid Filaments 96
4.1 Reasons to Use the Hybrid Filaments 96
4.2 Stability of the Cross-Bridge Position in the Absence of ATP 97
4.3 ATP-Induced Cross-Bridge Movement 99
4.4 Interpretation of the Results Obtained 101
5 Experiments with Bipolar Thick Filaments Consisting of Rabbit Skeletal Muscle Myosin 102
5.1 Resumption of Experiments at JEOL Ltd 102
5.2 Problems with Bipolar Thick Filaments 102
5.3 Stability of the Cross-Bridge Position in the Absence of ATP 104
5.4 Amplitude of the ATP-Induced Cross-Bridge Movement 105
5.5 Reversal in the Direction of ATP-Induced Cross-Bridge Movement Across the Filament Bare Region 107
5.6 Reversibility of the ATP-Induced Cross-Bridge Movement 108
5.7 Interpretation of the Results Obtained 110
5.7.1 Relation to Previous Studies 110
5.7.2 Direct Evidence for the Cross-Bridge Recovery Stroke 110
5.7.3 Variation in the Amplitude of Cross-Bridge Movement 112
6 Future Prospects 112
References 113
Role of Titin in Skeletal Muscle Function and Disease 116
1 Introduction 116
2 Brief Overview of Titin’s Layout 117
3 Modulation of Titin’s Elasticity Through Isoform Diversity 117
4 Molecular Basis of Titin’s Elasticity 119
5 Stretch-Release Force Hysteresis of Titin Molecules 122
6 Titin-Based Protein Complexes as Stress Sensors 122
7 Titin-Associated Skeletal Muscle Diseases 125
8 Summary 128
References 128
Contractile Characteristics of Sarcomeres Arranged in Series or Mechanically Isolated from Myofibrils 134
1 Introduction 134
2 Methods 135
2.1 Isolation of Myofibrils 135
2.2 Isolation of Sarcomeres 136
2.3 Visualization of Myofibrils and Sarcomeres 137
2.4 Activation and Force Measurements 138
3 Results 138
3.1 Force and SL Changes Produced by Myofibrils 138
3.2 Force and Length Changes Produced by Isolated Sarcomeres 141
3.3 Force–SL Relation 142
3.4 A-Band Movements and Half-Sarcomere Dynamics 143
4 Discussion 146
4.1 Myofibril Experiments 146
4.2 Sarcomere Experiments 147
4.3 Half-Sarcomere Dynamics 148
4.4 Summary 148
References 149
The Force–Length Relationship of Mechanically Isolated Sarcomeres 152
1 Introduction 152
2 Methods 157
3 Results 159
3.1 Force Enhancement 159
3.2 Force Depression 161
4 Discussion 164
References 170
Extraction and Replacementof the Tropomyosin–Troponin Complexin Isolated Myofibrils 173
1 Introduction 173
2 Methods and Results 175
3 Discussion 181
References 183
Stretch and Shortening of Skeletal Muscles Activated Along the Ascending Limb of the Force–Length Relation 185
1 Introduction 185
2 Methods 186
2.1 Preparation of Myofibrils 186
2.2 Solutions 187
2.3 Experimental Setup 187
2.4 Experimental Protocol 189
2.5 Data Analysis 189
3 Results 190
3.1 Myofibril Activation and History Dependence of Force Production 190
3.2 The Force–SL Relation and SL Dispersion 190
4 Discussion 193
4.1 History-Dependent Properties 193
4.2 SLdis and Non-Uniformity 196
4.3 Cross-Bridges Deactivation and Force Depression 196
4.4 Summary 197
References 198
Cross-Bridge Properties in Single Intact Frog Fibers Studied by Fast Stretches 200
1 Introduction 201
2 Methods 202
3 Results 203
3.1 Critical Force and Critical Length on the Tetanus Rise in Normal Ringer and BDM Treated Fiber 204
3.2 Effects of Tonicity 205
3.3 Effects of Temperature 207
4 Discussion 208
5 Conclusion 212
References 213
Crossbridge and Non-crossbridge Contributions to Force in Shortening and Lengthening Muscle 215
1 Introduction 216
1.1 Background 216
2 Aim 216
3 Materials and Methods 216
4 Tension Response During a Ramp Length Change 217
4.1 General Features 217
4.2 P2 Transition and the Force–Velocity (F–V) Relation 218
4.2.1 The P1 Transition 220
5 Crossbridge Modelling 221
6 Non-crossbridge Contribution 223
6.1 Experimental Findings 223
6.2 Mechanism(s) for the Continued Tension Change 225
6.2.1 Sarcomere Instability 225
6.2.2 Thin Filament Deactivation 226
6.2.3 Stiffening of Non-crossbridge Elements 226
6.3 Implications 227
References 227
Short-Range Mechanical Properties of Skeletal and Cardiac Muscles 230
1 Introduction 230
2 Short-Range Mechanical Properties are a General Feature of Muscle 231
3 Molecular Mechanism 232
3.1 Evidence Supporting a Cross-Bridge Mechanism 232
3.2 Calcium Dependence 232
3.3 Myosin ATP-ase Inhibitors 233
4 Dependence on Mechanical History 234
4.1 Recovery Rate 236
5 The ‘Range’ of the Short-Range Response 237
5.1 Difficulty of Analysis 237
6 Velocity-Dependence 239
7 Second Component 241
8 Relaxed Muscle 243
9 Cardiac Muscle 245
9.1 Myosin Heavy Chain Effects 247
10 Physiological Significance 247
10.1 Skeletal Muscle 249
10.2 Cardiac Muscle 249
References 250
Crossbridge Mechanism(s) Examinedby Temperature Perturbation Studies on Muscle 254
1 Introduction 254
2 Materials and Methods 255
2.1 Mechanical Recording System 255
2.2 Temperature-Jump Technique 255
2.3 Intact Fiber Experiments 256
2.4 Skinned Fiber Experiments 256
2.5 Some General Considerations 257
3 Temperature Dependence of Isometric Force 257
3.1 Intact Muscle Fibers 257
3.2 Skinned Fibers 259
4 Tension Responses to Temperature-Jump (T-Jump) 260
4.1 Effects of Pi and ADP 260
4.2 Effect of Strain (During Shortening and Lengthening) 262
4.3 Kinetic Simulation of Basic Findings 263
5 General Discussion 265
5.1 Comparison with Other Studies 267
5.2 Mechanism of Endothermic Force Generation 268
5.3 Some Implications 269
References 270
Efficiency of Cross-Bridges and Mitochondria in Mouse Cardiac Muscle 274
1 Introduction 275
2 Methods 276
2.1 Papillary Muscle Preparation 276
2.2 Experimental Apparatus 276
2.3 Efficiency Calculations 277
2.4 Data Normalization and Statistical Analysis 277
3 Results 277
4 Discussion 279
4.1 Efficiency of Work Production by Cross-Bridges 279
4.2 Efficiency of Mitochondrial Oxidative Phosphorylation 281
5 Conclusion 283
References 283
Mechanisms of Skeletal Muscle Weakness 286
1 Introduction 286
2 The Usage of Intact Single Muscle Fibers as an Experimental Tool 287
3 The Intracellular Activation-Contraction Pathway in Skeletal Muscle Cells 288
4 Skeletal-Muscle-Specific Tfam Deficient Mice: A Mitochondrial Myopathy Model that Displays Muscle Weakness Due to Decreas 289
5 Skeletal Muscle of Cold-Acclimated UCP1 Deficient Mice Displays Muscle Weakness Due to Defective Function of the SR Ca2+ 293
6 Muscle Weakness After Fatiguing Stimulation Can Be Due to Either Decreased SR Ca2+ Release or Reduced Myofibrillar Ca2 294
7 Concluding Remarks 298
References 299
Stretch-Induced Membrane Damage in Muscle: Comparison of Wild-Type and mdx Mice 304
1 Stretch-Induced Muscle Damage 304
2 Duchenne Muscular Dystrophy and the mdx Mouse 305
3 The Mechanical Properties of the Surface Membrane 307
4 What Happens to the Mechanical Properties of the Membrane When Dystrophin Is Missing? 311
5 What Causes Membrane Damage After Stretched Contractions? 313
6 Repair of Membrane Damage 315
7 Why Is Membrane Permeability Greater in mdx Muscle? 316
References 317
Cellular and Whole Muscle Studies of Activity Dependent Potentiation 321
1 Introduction 322
2 Preparations 322
2.1 In Vivo 322
2.2 In Situ 323
2.3 In Vitro 323
3 Definitions of Terms 324
3.1 Twitch 324
3.2 Tetanic Contraction 324
3.3 Activity Dependent Potentiation 325
3.4 Staircase 326
3.5 Posttetanic Potentiation 327
3.6 Postactivation Potentiation 327
4 Historical Perspective 328
5 Excitation–Contraction Coupling 328
6 Mechanisms of Activity Dependent Potentiation 330
6.1 Phosphorylation of the Regulatory Light Chains of Myosin 330
6.2 Myosin Light Chain Kinase 330
6.3 Dephosphorylation of Regulatory Light Chains 331
6.4 Increased Ca2+ Sensitivity 332
6.4.1 Cross-Bridge Kinetics 332
6.4.2 Disordered Myosin Heads 333
6.4.3 Ca2+ Also Causes Increased S1 Mobility 334
6.5 Alternative Mechanisms of Potentiation 334
7 Mechanical Features of Activity Dependent Potentiation 335
7.1 Magnitude of Isometric Force Change 335
7.2 Twitch Shape 336
7.3 Time Course of Enhancement and Its Dissipation 336
7.4 Dynamic Contractions Are Also Potentiated 336
7.4.1 Is Peak Velocity Slowed by Regulatory Light Chain Phosphorylation? 336
7.5 Frequency Dependence of Activity Dependent Potentiation 338
8 Interactions and Factors Affecting Potentiation 339
8.1 Length Dependence of Activity Dependent Potentiation 340
8.2 Temperature and Activity Dependent Potentiation 341
8.3 pH and Mobility of the Myosin Heads 342
9 Interactions of Fatigue and Activity Dependent Potentiation 343
10 Less Potentiation with Inactivity 344
10.1 Is Aging Just a Case of Less Activity? 344
11 Summary 344
References 345