THE INITIAL RATES OF SWELLING OF ISOLATED MUSCLE AND THEIR RELATION TO THE OSMOTIC EXCHANGES WITHIN THE FROG

Abstract

Gastrocnemii and upper-leg muscles were placed in various solutions of NaCl and gelatin. The initial exchanges of water were measured by frequent weighings, and occurred in proportion to the surface area of the muscle and to the square root of the duration of immersion. Osmosis at different concentrations of NaCl was linearly related to the concentration except in extreme dilutions, where osmosis was exceptionally rapid. When gelatin was present at any concentration of NaCl, the rate of osmosis inward was much reduced. The rates were slightly different at each concentration from those for skinless frogs. From the data for the initial rates of osmosis into each frog tissue that has been studied, osmotic constants was calculated, and the concentrations at which no exchanges of water occur are compared. The initial rates of diffusion of chloride into some of the same tissues are likewise compared by calculating diffusion coefficients. By means of numerical relations, the relative distributions of water among various tissues can be estimated from the initial rates of osmosis manifested upon immersion of these tissues in a common medium. The forces attracting and holding water in tissues are under certain conditions proportional to these initial rates of osmosis.