Kinetics of Release of Radioactive Sodium, Sulfate and Sucrose From the Frog Sartorius Muscle

Abstract

The kinetics of release, after a period of equilibration, of Na24, S35O4 and C14 sucrose were studied in the isolated frog sartorius. The amount of Na24 released quickly (determined by graphical analysis) was found to correlate quite well (correlation coefficient = .91) to the total amount of sulfate and sucrose in the sartorius at the beginning of the washout period. The diffusion coefficients for the 3 substances in the major portion of the extracellular space, comprising the fast phase of release, were calculated. These values when expressed as % of the analogous value in free solution are 67, 93, and 63 for Na24, S35O4 and C14 sucrose,respectively. The average flux of Na across the cell membranes was calculated to be 15 x 10-12 moles/cm2/second.