Key result
Nebulin deficiency in 1-day-old mice resulted in a 65% reduction in isometric force, a 57% decrease in the rate of force redevelopment, and an 80% decrease in maximum power compared to wild-type.
Why the study?
Does nebulin deficiency alter the mechanical and kinetic properties of the actomyosin motor in skeletal muscle?
Does nebulin deficiency alter the mechanical and kinetic properties of the actomyosin motor in skeletal muscle?
Effect estimate: 65% reduction
Nebulin plays a direct role in promoting strong actomyosin interactions that are responsible for force and power production in skeletal muscle.
Nebulin supports actomyosin force generation in neonatal skeletal muscle; leaves open translation to human myopathy therapies.
The role of the actin filament-associated protein nebulin on mechanical and kinetic properties of the actomyosin motor was investigated in skeletal muscle of wild-type (wt) and nebulin-deficient (nebulin(-)(/)(-)) mice that were 1 d old, an age at which sarcomeric structure is still well preserved. In Ca2+-activated skinned fibers from psoas muscle, we determined the Ca2+ dependence of isometric force and stiffness, the rate of force redevelopment after unloaded shortening (k(TR)), the power during isotonic shortening, and the unloaded shortening velocity (V(0)). Our results show a 65% reduction in isometric force in nebulin(-)(/)(-) fibers at saturating [Ca2+], whereas neither thin-filament length nor the Ca2+ sensitivity of the contractile system is affected. Stiffness measurements indicate that the reduction in isometric force is due to a reduction in the number of actin-attached myosin motors, whereas the force of the motor is unchanged. Furthermore, in nebulin(-)(/)(-) fibers, k(TR) is decreased by 57%, V(0) is increased by 63%, and the maximum power is decreased by 80%. These results indicate that, in the absence of nebulin, the attachment probability of the myosin motors to actin is decreased, revealing a direct role for nebulin in promoting strong actomyosin interactions responsible for force and power production.
No takes yet. Share an insight, caveat, or question.
Bang et al. (2009) studied Nebulin deficiency. Nebulin deficiency vs. Wild-type was evaluated on Isometric force at saturating [Ca2+] (65% reduction). Nebulin deficiency in 1-day-old mice resulted in a 65% reduction in isometric force, a 57% decrease in the rate of force redevelopment, and an 80% decrease in maximum power compared to wild-type.
Synapse has enriched 4 closely related papers on similar clinical questions. Consider them for comparative context: