The electron-microscopic stucture and chemical composition of the isolated sarcolemma of the rat skeletal muscle cell

Purified tubular membranes prepared by extracting rat skeletal muscle cell fragments with buffered 0.4 M LiBr solution have been shown by electron microscopy to retain the major three layers (outer network of collagen fibrils, middle basement membrane, and inner plasma membrane) of the sarcolemma of the intact muscle cell. A chloroformmethanol mixture destroyed the plasma membrane, thereby extracting steroid, glyceride, phosphatide, protein and carbohydrate. A collagenase (EC 3.4.4.19) preparation appeared to digest not only the collagen network, but also the basement membrane. The lipid extractio or collagenase treatment did not destroy the tubular structure of the isolated membrane, but successive application of both treatments yielded only an amorphous precipitate.