Introduction: Because impaired excitation-contraction coupling and reduced sarcoplasmic reticulum (SR) Ca2+ release may contribute to the age-associated decline in skeletal muscle strength, we investigated the effect of aging on regulation of the skeletal muscle isoform of the ryanodine receptor (RyR1) by physiological channel ligands.
Methods: [3 H]Ryanodine binding to membranes from 8- and 26-month-old Fischer 344 extensor digitorum longus (EDL) and soleus muscles was used to investigate the effects of age on RyR1 modulation by Ca2+ and calmodulin (CaM).
Results: Aging reduced maximal Ca2+ -stimulated binding to EDL membranes. In 0.3 μM Ca2+ , age reduced binding and CaM increased binding to EDL membranes. In 300 μM Ca2+ , CaM reduced binding, but the age effect was not significant. Aging did not affect Ca2+ or CaM regulation of soleus RyR1.
Discussion: In aged fast-twitch muscle, impaired RyR1 Ca2+ regulation may contribute to lower SR Ca2+ release and reduced muscle function. Muscle Nerve 57: 1022-1025, 2018.
Keywords: aging; calcium; calmodulin; excitation-contraction coupling; ryanodine receptor; sarcoplasmic reticulum; skeletal muscle.
© 2018 Wiley Periodicals, Inc.