The present kinetic study of the permeability of rabbit erythrocytes has established that carrier systems are involved in the penetration of certain non-electrolytes. Saturation, competitive inhibition, and butanol inhibition kinetics were used to demonstrate the presence of carrier systems and the values of half-saturation constants (ø) were determined for the following water soluble non-electrolytes: glycerol, ethylene glycol, urea, and thiourea.
These non-electrolytes are commonly used in permeability studies because they are relatively non-toxic and their small sizes allow penetration of the erythrocyte membrane within a reasonable length of time
