Permeability of barnacle muscle fibers to water and nonelectrolytes

The permeability of isolated muscle fibers of the giant barnacle Megabalanus psittacus to water and nonelectrolytes was studied by determining their reflection and permeability coefficients. Reflection coefficients were obtained by comparing the osmotic fluxes produced by a test molecule to that produced by the impermeant sucrose molecule. Permeability coefficients were determined for measurements of tracer uptake. The results indicate that, in these fibers, nonelectrolyte permeability is closely related to lipid solubility and molecular size. A value of 2.16 X 10(-12) cm3/sec dyne for the hydraulic conductivity and a value of 10.45 X 10(-4) cm/sec for 3HHO permeability coefficient were obtained. The effect of membrane surface invaginations and clefts on the determination of permeability coefficients is discussed.