Examples of transverse sections of muscle from F1 mice with histochemical staining for myosin ATPase preincubated at a) pH 4.6 in EDL, b) pH 4.3 in EDL, c) pH 10.4 in EDL, d) pH 4.6 in SOL, e) pH 4.0 in SOL, f) pH 4.0 in EDL. Fiber types I, 2a, 2x, and 2b were identified in the SOL and fiber types I, 2x, and 2b were identified in the EDL. Serial sections in a), b), and c) show staining patterns of fiber types at different preincubations in the EDL. Although multiple preincubation conditions were used on serial sections, the section in d) demonstrates that all 4 fiber types in SOL could often be resolved at a single pH. The examples in e) and f) show the difference in capillarity between the two muscles. Section e) was selected because it shows the potentially high transverse nature of the capillary network in the SOL (from Luedeke et al. in review).

Transmission electron micrograph of a cross-section through the fast-twitch, white levator muscle from the swimming leg of the blue crab (micrograph by Kim-Laura Boyle).

Example of a tension record during a series of fatiguing contractions in isolated fast-twitch levator muscle from the blue crab. We use this type of experiment to examine muscle function during treatments that impair metabolic recovery. The tension can be seen to decline during each 45-s series of stimulations. The second series of contractions was collected 1 hour after the first, before metabolic recovery was complete (collected by Lisa Johnson).