Origin and composition of hepatic lymph proteins in the dog
Lymphology 4 (1971) ,  Pappenheimer (11) has shown that the walls of capillary vessels behaved as semipermeable membranes. Applying this concept to the transcapillary transfer of macromolecules, Grotte ( 4) and Mayer son et al. (8) measured the permeability of the dog's capillaries by means of the plasma versus lymph concentration ratios of dextran molecules of graded molecular size, after intravenous injection of the substance. Both workers concluded that
... concluded that capillary walls contained two kinds of pores of different size. The molecular sieve effect would be largely accounted for by a set of small pores having a radius of about 40 A according to Grotte ( 4) or 110 A according to Mayer son et al. (8). The data also required the assumption of the existence of larger pores, of undefined diameter, which would allow free passage to particles of any molecular size up to a mo!. weight of 300 000. It was also shown that each type of tissue had its own characteristic capillary permeability, that of the liver being greater than that of the small bowel, and the latter in turn exceeding the capillary permeability of the limbs or cervical region. Such differences would arise both from regional variations in the distribution density of the pores and from shifts in the ratio of large versus small pores, the pore sizes remaining constant. The findings described above were all obtained by using dextran molecules, but in theory they could equally well have been derived from a study of the plasma versus lymph concentration ratio of endogenous plasma proteins. This presentation will be concerned with an attempt in that direction, using as a model the plasma and hepatic lymph of the dog. Materials and Methods I. Surgery In twelve mongrel dogs a laparotomy was performed and the hepatoduodenal ligament was exposed by reclining the bowel to the left. A lymph vessel, efferent from a hepatic lymph node, was dissected free and cannulated by means of 0.8 mm bore polyethylene tubing. Lymphatic channels draining from the intestinal wall into the hepatic nodes were made visible by injecting a small amount of Patent Blue® dye into the bowel wall. By ligating all channels dyed by this procedure it was possible to reduce contamination of hepatic lymph with intestinal lymph to the desired minimum. Lymph was collected over a period of about one hour and, at mid-time, a sample of venous blood was secured for comparison. Permission granted for single print for individual use. Reproduction not permitted without permission of Journal LYMPHOLOGY.