Right Lymphatic Duct Distribution Volume in Dogs

Abstract

Steady-state ratios of the concentration in lymph to that in plasma were measured for 125 I-serum albumin after 4 days of equilibration in unanesthetized dogs. Subsequently, acute experiments 3-8 hours in duration were carried out in the same dogs under anesthesia to measure the exchange kinetics of 131 I-serum albumin in right duct lymph and thoracic duct lymph. The albumin distribution volume in the field of right lymphatic duct drainage was calculated and compared with the pulmonary interstitial fluid volume measured using 14 C-sucrose. For the right lymphatic duct, a single rate constant ( K R ) was sufficient to account for equilibration up to 3-8 hours. The mean value of K R was 2.35 x 10 -3 ± 0.99 x 10 -3 min -1 (half-time 5.6 ± 1.96 hours). In contrast, equilibration of thoracic duct lymph was multiexponential over this period. The concentration of 125 I-albumin in lung interstitial water was 74% of that in corresponding right duct lymph. At 3-8 hours (termination of the acute experiment), fractional equilibration of interstitial albumin calculated from 131 I-albumin wash-in kinetics was 0.33 ± 0.1 and that of right duct lymph was 0.34 ± 0.11, indicating that the K R measured for the latter reflects the equilibration process in lung interstitial fluid. The mean distribution volume drained by the right lymphatic duct was 0.92 ± 0.42 ml/kg. Subtracting the reported cardiac lymph distribution volume and correcting the remainder for albumin concentration relative to lymph suggests that about 28% of the lung lymph drains into the right lymphatic duct.