Diffusion of aldolase from rat skeletal muscle; an index of membrane permeability.

Abstract

It was shown previously that a protein, aldolase, flows from excised rat diaphragm incubated in a variety of media. Because muscle fibers are cut in this preparation there was some question about the absolute values of permeability of the diaphragm. These experiments have been repeated using a small muscle with two tendinous insertions, the peroneus longus. In addition to confirming increased permeability during anoxia, glucose lack, altered metabolism produced by transferring muscle to fresh media, and probable membrane depolarization by potassium, it was shown that there is no greater permeability in phosphate buffer than in bicarbonate buffer and that the aldolase in the effluent (as percentage of total muscle aldolase) decreases as the weight of muscle increases. The latter relation is predicted approximately from surface/volume ratio of cylindrical fibers which decreases as volume increases.