SLControl: PC-based data acquisition and analysis for muscle mechanics.

SLControl is a computerized data acquisition and analysis system that was developed in our laboratory to help perform mechanical experiments using striated muscle preparations. It consists of a computer program (Windows 2000 or later) and a commercially available data acquisition board (16-bit resolution, DAP5216a, Microstar Laboratories, Bellevue, WA). Signals from the user's existing equipment representing force, fiber length (FL), and (if desired) sarcomere length (SL) are connected to the system through standard Bayonet Neill Concelman cables and saved to data files for later analysis. Output signals from the board control FL and trigger additional equipment, e.g., flash lamps. Windows dialogs drive several different experimental protocols, including slack tests and rate of tension recovery measurements. Precise measurements of muscle stiffness and force velocity/power characteristics can also be accomplished using SL and tension control, respectively. In these situations, the FL command signal is updated in real time (at rates > or =2.5 kHz) in response to changes in the measured SL or force signals. Data files can be exported as raw text or analyzed within SLControl with the use of built-in tools for cursor analysis, digital filtering, curve fitting, etc. The software is available for free download at http://www.slcontrol.com.