[Use of a computer-controlled servo system to produce "ephysiological" contraction of isolated rat papillary muscle].

A computer-controlled servo system consisting of an ergometer with a force-displacement dual mode transducer, a Z-80 single-board microcomputer and a designed software was constructed. This servo system can be used to generate physiological contraction in isolated rat papillary muscle, in which the muscle went through a complete 4-phase cycle of force and length changes, similar to those undergone by muscle fibers in the beating heart during the cardiac cycle. This system is being used to investigate the tension-length relation and the network of isolated myocardium as well as the end-systolic tension-length relation and the force-velocity relation simultaneously.