Changes in the T-System of Muscle Fibres under the Influence of Influx and Efflux of Glycerol

Abstract

A STUDY of the permeability of isolated frog muscle fibres to glycerol, urea and its derivatives, amides and glycols led to the observation that fibres become filled with vacuoles, clearly visible under the light microscope, when they are returned to Ringer solution after being kept for 30–300 min in Ringer to which 220 mM of one of these non-electrolytes has been added^1,2. The changes in fibre structure begin 1–2 min after the fibre has been returned to normal Ringer solution and attain their maximum in 15–20 min. If the fibre is left in Ringer solution, these alterations either persist for many hours or disappear gradually so that 2–4 h later the fibre structure is completely or partially restored to normal. As a rule, however, the vacuolation disappears within 3–10 min if the fibre is returned to the same non-electrolyte solution the washing out of which led to vacuolation in the first place, or if it is transferred to Ringer solution with an equal concentration of another, more slowly penetrating, non-electrolyte.