Resealed fiber segments for the study of the pathophysiology of human skeletal muscle.

The usefulness of long fiber segments for the study of the pathophysiology of human skeletal muscle was evaluated. Immediately after biopsy, the fiber segments were depolarized. Within 3 hours the cut ends resealed, and if the segments were greater than or equal to 2.5 cm long they regained normal resting membrane potentials (i.e., negative to -80 mV). Miniature endplate potentials, endplate potentials, action potentials, the current-voltage relationship, and the resting intracellular Ca2+ concentration of the resealed fiber segments were similar to those in fibers that were intact from tendon to tendon. In addition, specific properties of intact fibers obtained from patients with various neuromuscular diseases were preserved in the resealed fiber segments prepared from the same patients or patients with the same diseases. These segments are easily obtained as a routine muscle biopsy performed under local anesthesia; they provide valuable preparations for the study of the pathophysiology of human skeletal muscle as well as for in vitro pharmacological tests.