CR-51-RBCS AND I-125 ALBUMIN AS MARKERS TO ESTIMATE LYMPH-DRAINAGE OFTHE PERITONEAL-CAVITY IN SHEEP

Cr-51-RBCs and I-125-albumin as markers to estimate lymph drainage of the peritoneal cavity in sheep. J. Appl. Physiol. 76(2): 867-874, 1994 . - The purpose of this study was to compare the use of I-125-labeled human serum albumin (I-125-HSA) and autologous Cr-51-labeled red blood cells (Cr-51-RBCs) as lymph flow markers to estimate lymph drainage o f the peritoneal cavity in conscious sheep. In one group, we assessed lymph drainage from the appearance of intraperitoneally administered t racer in the bloodstream. To determine distribution of drainage into d iscrete lymph compartments, in a second group of studies, lymph was co llected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in lymphatic drainage of the ovine peritone al cavity. Ringer lactate solution (50 ml/kg) containing 8-10 mu Ci ea ch of I-125-HSA and Cr-51-RBCs was infused into the peritoneal cavity. Lymph drainage was calculated by dividing the change in mass of trace r in the blood or lymph compartments by the average intraperitoneal tr acer concentration. In noncannulated animals, lymph drainage averaged over 6 h was higher with T-125-HSA as tracer (1.35 +/- 0.12 vs. 0.62 /- 0.19 ml.h(-1).kg(-1) with Cr-51-RBCs). A similar pattern was noted in terms of drainage into the caudal lymphatic (0.89 +/- 0.23 and 0.52 +/- 0.19 ml.h(-1).kg(-1) with I-125-HSA and Cr-51-RBCs, respectively) and thoracic duct (0.16 +/- 0.06 and 0.05 +/- 0.02 ml.h(-1).kg(-1) wi th I-125-HSA and Cr-51-RBCs, respectively). Analysis of I-125-HSA and Cr-51-RBC concentrations in lymph and intraperitoneal fluid suggested sieving of RBCs at the diaphragmatic stomata or lymph nodes. Using I-1 25-HSA as tracer and combining data from noncannulated and cannulated sheep, we estimated peritoneal lymph drainage to be 1.35 ml h(-1) kg(- 1), with 66% of this flow drained by the caudal vessel, 22% by the par asternal pathway (right lymph duct), and 12% by the thoracic duct.