Angela J Gaboardi1, Jochen Kressler2, Teresa K Snow1, Edward M Balog1. 1. School of Applied Physiology, Georgia Institute of Technology, 281 Ferst Drive, Atlanta, GA, 30332, USA. 2. Exercise and Nutritional Sciences Department, School of Health and Human Services, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA.
Abstract
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.
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 RyR1Ca2+ regulation may contribute to lower SR Ca2+ release and reduced muscle function. Muscle Nerve 57: 1022-1025, 2018.