PHYSIOLOGIC IMPORTANCE OF LYMPH 



I06l 



trypsinase which were present in the exudates. Free- 

 man & Schecter (77) tested leg lymph obtained 

 from dogs whose hind legs were traumatized or heated 

 and found that it produced an increase in permeability 

 as judged by leakage of dye when injected into re- 

 cipient animals. Arterial and venous serum and 

 plasma also contained a similar factor which increased 

 capillary permeability, and the authors concluded 

 that it was likely that the presence in lymph of a 

 substance capable of producing an increase in capil- 

 lary permeability is dependent upon the appearance, 

 after trauma, of blood plasma in the lymph draining 

 from the extremity. On the other hand, Lindner 

 et al. (126) failed to find any evidence of a perme- 

 ability factor either in lymph or plasma in shock 

 produced by manipulation of the intestine. Their 

 experience was similar to the earlier one reported 

 by Dragstedt & Mead (57), who produced shock by 

 sustained trauma with a padded hammer to one or 

 both hind legs, by trauma to the intestine, or by a 

 combination of the two methods. 



Burns 



Some work has been done on the study of lymph 

 in burns. Aldrich (2) collected leg lymph from burned, 

 anesthetized dogs and perfused it through rabbit 

 ears. Blood flow as measured by drop rate definitely 

 decreased when lymph from burned animals was 

 used as compared to lymph from healthy clogs. No 

 attempt was made to identify the vasconstrictor 

 substance. 



Glenn and his colleagues, in Drinker's laboratory, 

 studied the changes in lymph composition after leg 

 burns produced with hot water in calves (85, 86, 

 170). Cervical and leg lymph was followed. Lymph 

 flow in the burned legs was significantly increased as 

 was the protein concentration of the leg lymph. 

 Cervical lymph, however, did not show the increase 

 in protein. Electrophoretic studies showed the occur- 

 rence of a new protein in the lymph from the burned 

 leg, a component migrating with half the speed of 

 7-globulin. Cope & Moore (44) also reported a signifi- 

 cant increase in capillary permeability following hot 

 water burns of legs of dogs. They injected radioactive 

 colloidal dyes into the blood stream and measured 

 their appearance in leg, cervical, and thoracic duct 

 lymph before and after the burn. They also injected 

 radioactive bromine, which they found to appear in 

 lymph from the three areas within 5 min and to 

 reach equilibrium with serum in 20 min. In contrast, 

 the colloidal dyes were slower in appearance in 



lymph and no equilibrium was established with serum 

 under control conditions. Following the burn, the 

 concentration of radioactive colloids in lymph of the 

 burned leg rose abruptly and approached that 

 encountered after injection of radioactive bromine. 

 The specific activity of protein was actually higher 

 in lymph than in serum after the burn. In confirma- 

 tion of Glenn et al., they also found that the increased 

 capillary permeability was usually restricted to the 

 burned leg. A rise in colloid concentration in cervical 

 lymph was observed in only one dog. 



Permeability Factors 



During the last decade, considerable interest has 

 been aroused in the presence in plasma of endogenous 

 substances which, when activated, induce pathologi- 

 cal increases in capillary permeability (144). Two 

 classes of natural mediators have been suggested: 

 7) the pharmacologically active amines, histamine, 

 and hydroxytryptamine; and 2) proteases and prod- 

 ucts of proteolysis. This latter group includes the 

 proteases of plasma (plasmin, the serum globulin 

 permeability factors, and polypeptides like leuko- 

 taxine and bradykinin). The groups overlap in that 

 polypeptides may act as histamine liberators. There 

 is direct and indirect evidence that these substances 

 participate in the mediation of the response to 

 injury, but much more evidence is needed to define 

 their role in the healthy animal and in animals 

 suffering from hemorrhage, burn, or other trauma. 

 It would be interesting to extend the observations 

 of Miles & Wilhelm (144) to other substances, 

 species, and experimental conditions. These investi- 

 gators showed the presence in the guinea pig of the 

 precursor (pro-PF) and the inhibitor (IPF) of one of 

 the globulin permeability factors, both in intercellular 

 perfusates of skin and in normal lymph from the 

 cervical lymph ducts (143). It appears that the 

 proteins constituting the pro-PF/IPF system of the 

 blood, like other plasma proteins, pass continuously 

 via the extravascular tissues to the lymph, and that 

 the extravascular tissues, including the outer surface 

 of the capillary wall, are bathed in tissue fluid con- 

 taining pro-PF. 



PERMEABILITY OF LYMPHATIC VESSELS 



Although a considerable amount of work has been 

 done relative to the permeability of blood vessels, we 

 have very little definitive information regarding 



