Muscle chamber with strain gauge adapted for isotonic/isometric recording.

Simple devices are described that can facilitate student experiments on mechanical and electrical aspects of muscle contraction, for example, of isolated preparations such as frog gastrocnemius and sartorius muscles and gut. The system includes a general-purpose preparation bath that was previously described for electrophysiological observations with suction electrodes [D.M. Easton. Am.J. Physiol. 265 (Adv. Physiol.Educ. 10): S35-S46, 1993]. A tower installed in the bath allows the muscle to be oriented vertically but completely submerged in a limited volume. Recording of isotonic contraction, which is the more familiar behavior of skeletal muscle, is made convenient by an accessory to convert the commonly available Statham force transducer to isometric recording. Phenomena not conveniently accessible by isometric recording, such as muscle work, and also the length-tension relation, not ordinarily observed for isotonic contraction, can be demonstrated.