1056 



HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



free fluid contained in the larger collecting ducts of 

 the kidney. The average concentration of inulin in 

 renal lymph from 8 dogs was found to be 82.5 mg 

 per cent or 94 per cent of the plasma concentration. 

 The authors considered these results as evidence that 

 the composition of renal lymph is determined by the 

 character of both tubular reabsorbed fluid and renal 

 blood plasma. If it were derived exclusively from the 

 renal tubular reabsorbed fluid, its inulin content 

 would be practically nil and if it were derived exclu- 

 sively from renal blood plasma, its inulin content 

 would be equal to that present in plasma. 



Swann and his colleagues (205) reported measure- 

 ments on renal capsular lymph from 5 dogs. Lymph 

 flow was between o. 1 to 0.3 ml per hour. They also 

 found urea concentration of renal lymph to be higher 

 than plasma and glucose concentration to be lower. 

 They found total protein content to be quite constant 

 at about 3.2 g per cent, about half that present in 

 plasma, and failed to observe the inverse relation of 

 protein content to lymph flow reported by Sugerman 

 et al. Electrophoretic separation of the proteins showed 

 that their distribution in lymph was similar to that in 

 plasma. 



About 5 years ago, my colleague, Dr. S. J. LeBrie, 

 and I began a comprehensive study of renal lymph as 

 part of a general study of lymph and lymphatics. We 

 have collected renal capsular lymph in a variety of 

 experimental situations which will be detailed below. 

 We have found the lymph flow to be quite variable 

 and unrelated to sex, age, or size of the animal. The 

 average control flow for 63 dogs studied up to the 

 present time is 0.0128 ml per min or 0.768 ml per 

 hour. Total protein concentration for 40 dogs averages 

 2.76 g per 100 ml or about half of plasma concen- 

 tration. 



We find protein distribution to be similar to that 

 of plasma, confirming the findings of Swann et al. 

 All plasma proteins, including fibrinogen, are present 

 in renal lymph. Potassium concentrations appear to 

 be identical in lymph and plasma. We previously 

 reported (121) that the average lymph sodium con- 

 centration for 30 dogs was 1 1.3 per cent higher than 

 in plasma. Addition of more data and refinement of 

 experimental procedures suggests that this value may 

 be too high and the difference may or may not be sig- 

 nificant. Limited data on osmotic pressure also have 

 been equivocal. Data on 30 dogs show lymph chloride 

 concentration to average 13 per cent higher than 

 plasma, a difference which is statistically significant. 

 We have some indication that bicarbonate concen- 

 tration is lower in lymph than in plasma. Obviously 



we need more data to clarify the situation with respect 

 to these constituents. These data are being accumu- 

 lated. 



It is of interest to compare renal lymph flow with 

 urine flow in the same kidney. It is reasonable to 

 assume that there are at least ten lymphatics draining 

 each kidney. Using the average flow which we ob- 

 tained from one lymphatic, the average total lymph 

 flow from both kidneys would amount to o. 1 28 ml 

 per min, which is approximately half of the average 

 amount of urine flow. In some animals with high 

 lymph flows, the amount of capsular lymph drained 

 equals the amount of urine formed. Similar admittedly 

 rough calculations for protein yield a value of 10.2 g of 

 protein returned to plasma per day via capsular 

 lymphatics of both kidneys. It should be emphasized 

 that these are average values for the anesthetized dog 

 and probably reflect minimum levels. 



Renal lymph flow is markedly increased by raising 

 venous pressures. This was first shown by Schmidt & 

 Hayman (195) and later confirmed by Katz & Cockett 

 (109) and by us (123). Schmidt and Hayman analyzed 

 the changes in thoracic duct lymph flow in eviscerated, 

 hepatectomized, and uninephrectomized dogs follow- 

 ing ligation of the remaining functional renal vein. 

 They concluded that the increase in renal lymph flow 

 was responsible for the observed rise in thoracic duct 

 lymph flow when venous pressure was raised. Katz 

 and Cockett likewise concluded that changes in renal 

 lymph were responsible for changes in thoracic duct 

 lvmph which they observed. They observed an in- 

 crease in thoracic duct lymph flow and sodium concen- 

 tration as well as a decrease in urinary flow and 

 sodium concentration when venous pressure was 

 raised. The changes occurred only when the kidneys 

 were intact. Haddy and his colleagues (94), in ex- 

 periments designed to study pressure and flow rela- 

 tionships in the kidney, also reported that renal 

 lvmph flow increased as a function of venous pressure. 

 In our experiments, we collected capsular lymph and 

 raised the venous pressure by partially occluding the 

 inferior vena cava with a balloon catheter. We also 

 measured protein and electrolyte changes. Renal 

 lvmph flow increased about five times during the 

 periods of increased venous pressure and the flow 

 from one lymphatic equaled and often exceeded 

 urine flow from the same kidney. Electrolytes and 

 protein levels changed proportionately except at high 

 venous pressure levels (30-35 cm H a O) when dispro- 

 portionately high levels of protein were found in renal 

 lymph. 



In discussing the significance of the changes in lym- 



