Aged muscle lacks sparks

Muscle activity is driven by spikes of calcium release. Weisleder et al. (page 639) find that aged muscles, when compared with young muscles, have reduced Ca²⁺ release following stimulation. The dampened response may be caused by a failure to maintain robust membranous compartments that can respond to an input with a single output.

Previous work from the group showed that Ca²⁺ sparks can be induced in skeletal muscle by osmotic shock and that the sparks resemble those produced during exercise. The group has now found that, compared with young tissue, aged muscle releases fewer of these Ca²⁺ sparks. The poor response may be a result of the poor state of the sarcoplasmic reticulum (SR) network in aged fibers. This network stores Ca²⁺ and releases it in response to incoming nerve signals, but...