Real-time measurement of sarcomere length changes during contraction of single heart cells using a phase-locked loop

We have to date investigated cardiac mechanics at the cellular level by monitoring cell force and cell length. However, the understanding of the biophysics of twitch contractions of cardiac muscle ultimately requires real time measurements of sarcomere length. In this report, we describe improvements to our instrumentation system which utilize a phase locked loop to track the changes in sarcomere length during a twitch contraction.