PHYSIOLOGIC IMPORTANCE OF LYMPH 



10 



3D 



ent in 3 dogs and left ventricular subendocardial 

 hemorrhages in 7 of 1 7 dogs. They describe other 

 changes and point out the merit of further investiga- 

 tion of cardiac lymphatics and the relationships of dis- 

 turbances of their function to pathologic states. 

 Rusznyak and co-workers have also described the 

 results of similar experiments done by their group. 

 They report in detail the electrocardiographic changes 

 seen after cardiac lymphatic obstruction and after 

 ligation of the coronary sinus and cardiac lymph 

 nodes. They also emphasize the possibility that lym- 

 phatic congestion may play an important role in the 

 pathogenesis of mitral stenosis and other cardiac 

 diseases. 



Drinker and his colleagues (64) are the only group 

 to date who have collected and studied cardiac 

 lymph. They reported measurements of flow in 10 

 dogs as varying between 0.31 to 1.65 ml per hour 

 (average 0.8 ml /hour) with no correlation between 

 dog weight, heart weight, blood pressure, and lymph 

 flow. Since only one lymphatic was cannulated and 

 since there are usually two main efferent trunks, the 

 total flow was probably approximately twice the 

 values obtained. This would mean that about 60 to 

 70 per cent of the total right lymph duct flow comes 

 from the heart. The lymph always contained a rela- 

 tively high concentration of protein. The average for 

 18 dogs was 3.69 per cent with a range between 2.50 

 to 4.73 per cent. Since right duct lymph contains 

 approximately the same concentration, this suggests 

 that cardiac and lung lymph have about the same 

 concentration of protein. This is also supported by the 

 values obtained by Warren & Drinker (216) in collec- 

 tion from a large lymphatic in the anterior mediasti- 

 num. Thus there is in the heart, as in all other tissues 

 studied, a continuous leakage of protein from the 

 capillaries and the rhythmic contractions of the car- 

 diac muscle insure its rapid removal by the extensive 

 lymphatic plexuses. These investigators also found 

 that cardiac lymph flow increased after the injection 

 of epinephrine and ephedrine, the rise appearing to be 

 correlated to the increased cardiac work. Experiments 

 with a Starling heart-lung preparation designed to 

 simulate exercise (increased input and peripheral 

 resistance and addition of epinephrine) showed a 

 marked increase in lymph flow to 24 ml per hour. As 

 Yoffey & Courtice (234) point out, even if we accept 

 a figure of 18 ml per hour, a hound engaged in a 12 

 hours' chase would be putting out 216 ml of cardiac 

 lymph. With a heart weight of 91 g, this would mean 

 2.4 ml of lymph per g of heart during the 1 2 hours. 



Renal 



Although a relatively extensive literature has ac- 

 cumulated concerning the distribution of kidney 

 lymphatics and their possible role in clinical disorders 

 (88), the physiological role of renal lymph is less well 

 documented. This is due to the difficulty in cannulat- 

 ing the vessels because of their location and extremely 

 small size. The main hilar trunks are particularly in- 

 accessible to cannulation, whereas capsular lym- 

 phatics, although more accessible, are quite small and 

 difficult to cannulate. This has led some investigators 

 to the highly unphysiologic compromise of eviscerat- 

 ing animals and collecting thoracic-duct lymph on 

 the assumption that this lymph was now derived 

 solely from the kidney. 



The first physiological experiments on renal lym- 

 phatics were made by Ludwig & Sawarykin (129), 

 who showed that ligation of a ureter was followed by 

 dilatation of efferent renal lymphatics. They did not 

 study lymph flow or composition under these condi- 

 tions, but their experiments form the basis of a more 

 recent elaborate study by Babies and his collaborators 

 (7, 8), whose work will be discussed later. Sugerman 

 et al. (204) were probably the first to collect renal 

 lymph directly and begin its characterization in dogs. 

 They cannulated both capsular and hilar lymphatic 

 trunks and reported a wide fluctuation in flow and 

 protein concentration. The slower the lymph flow, 

 the greater was the concentration of protein. Their 

 average figure for flow from 1 1 dogs was 0.0232 g per 

 min (1.392 g/'hour) and for protein concentration 

 1 .84 g per cent. Of interest was the finding of a higher 

 average urea concentration in renal lymph (69.7 

 mg%) than in plasma (53.1 mgTt). In some animals, 

 the lymph urea concentration was considerably higher 

 than that in plasma of the renal artery or vein. These 

 findings posed two questions: /) Do the renal lym- 

 phatics drain only the larger collecting ducts of the 

 kidney, thus accounting for the high urea content of its 

 lymph? 2) Is renal lymph derived from tubular reab- 

 sorbed fluid, the blood plasma, or from both types of 

 fluid? Attempts to answer these questions were made 

 by Kaplan et al. (107) who determined and compared 

 the glucose content of renal and cervical lymph sam- 

 ples as well as their inulin content during an intra- 

 venous infusion of inulin. The average concentration 

 of glucose in 8 renal lymph samples was 92.7 mg per 

 cent and 10 1.9 mg per cent in 8 cervical lymph sam- 

 ples. They concluded that this high glucose concen- 

 tration in renal lymph suggests that renal lymph could 

 not be derived exclusively from the relatively sugar- 



