Does "Restricted Diffusion" Occur in Muscle Capillaries?

Abstract

An experimental procedure ("Indicator Duffusion Method") is described which permits evaluation of the permeability of muscle capillaries to sucrose and inulin (in the dog). In experiments where the ratio between the permeability coefficients was determined this ratio did not differ significantly from the ratio between the coefficients for free diffusion. This finding was unexpected for a membrane with pores of about 70 A units diameter (as deduced by Renkin and Pappenheimer, Ergebn. Physiol. 1957). One explanation for the deviating results may be that the last mentioned authors used van''t Hoff''s law (n = R.T.C.) without introducing the reflection coefficient (G). The pore theory thus has not yet gained experimental support as far as muscle capillaries are concerned.