Functional control of myosin motors in the cardiac cycle by Malcolm Irving instant download

Functional control of myosin motors in the cardiac cycle by Malcolm Irving instant download

Contraction of the heart is driven by cyclical interactions between Introductionmyosin and actin flaments powered by ATP hydrolysis. The modular The modular structure structure of heart muscle and the organ-level synchrony of the of heart muscleheartbeat ensure tight reciprocal coupling between this myosin ATPase The cardiac cycle at the filament levelcycle and the macroscopic cardiac cycle. The myosin motors respond to the cyclical activation of the actin and myosin flaments to drive Thin filament regulationthe pressure changes that control the infow and outfow valves of the Thick filament regulationheart chambers. Opening and closing of the valves in turn switches The myosin motor cyclethe myosin motors between roughly isometric and roughly isotonic Synchrony of motor and contraction modes. Peak flament stress in the heart is much smaller cardiac cyclesthan in fully activated skeletal muscle, although the myosin flaments The Frank–Starling lawin the two muscle types have the same number of myosin motors. Heart failure and therapyCalculations indicate that only ~5% of the myosin motors in the heart are needed to generate peak systolic pressure, although many more motors Conclusionsare needed to drive ejection. Tight regulation of the number of active motors is essential for the efcient functioning of the healthy heart — this control is commonly disrupted by gene variants associated with inherited heart disease, and its restoration might be a useful end point in the development of novel therapies.