Fig. 1.

Contractile and ultrastructural properties of DG- and α7-deficient skeletal muscle. (A–D) Specific force (A and B) and force deficit (C and D) after 2 lengthening contractions of the EDL muscle from α7-null (α7 KO) and DG-null (DG KO) mice were compared to those for littermate controls. (*, P < 0.05.) All data are presented as the mean ± SD. (E–G) Ultrastructure of quadriceps muscle from 5-week-old control (E), integrin α7-null (F), and DG-null (G) mice in the absence of exercise. (H) Ultrastructure of exercised quadriceps muscle from DG-null mice immediately after downhill treadmill running. Black arrowheads, basal lamina; white arrowhead, sarcolemma; black asterisk, site of separation of the sarcolemma and the basal lamina; dashed line, outline of the disrupted sarcolemma; black arrow, disruption of sarcomere structure.