THE PERMEABILITY OF THE PLASMA-LYMPH BARRIER OF THE SMALL INTESTINE OF VARIOUS SPECIES TO MACROMOLECULES

Abstract

The filtration coefficients  of  polyvinylpyrrolidone (PVP) of molecular weight 10,000-110,000 were measured at the plasma-lymph barrier of the upper smalI intestine of rabbits, rats and cats. For this purpose the animals were given intravenous injec­ tions or infusions of PVP in such a way as to pro­ duce a constant blood level; PVP concentrations were measured in lymph obtained by cannulating   the mesenteric duct and also in the plasma. In these species low molecular weight PVP had a filtration coefficient  of  0.85 - 0.64,  while high  molecular weight PVP (MW 110,000) either had a very low filtration coefficient  -  0.22  -  or  was not  detectable in the intestinal lymph. The three species, represent­ ing herbivores, omnivores and carnivores, showed no differences in  the  penetration  behavior  of  PVP, i.e., in the permeability of  the  plasma-lymph  barrier to  macromolecules.