Articles

OXYGEN TENSION OF NEARLY PURE PULMONARY LYMPH IN UNANESTHETIZED SHEEP

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Abstract

Bergofsky (1, 2) measured the oxygen tension (Po2) of thoracic duct (TD) lymph and equated it with average tissue Po2 • Other workers have made similar comparisons for kid­ ney (3) and intestinal tract (4).

Said and Banerjee (5) used this concept to calculate the fraction  of  lung  lymph  in  right lymphatic  duct  (RLD)  lymph  in  anesthetized  dogs. They found the average Po2 = 75 torr; the same as the average arterial Po2 and  considerably  higher  than  TD Po2 .  Using standard mixing equations, assuming pure lung lymph  Po2  equaled  alveolar  gas Po2  and  non-respira­ tory  lymph  equaled  TD  Po2    they  computed  that  53% of  RLD  lymph  came from  the lung.

Recently, Meyer and Ottaviani (6) made similar Po2 measurements both for RLD and TD normally and in acute edema. They confirmed the apparently high Po2 in RLD lymph and calculated that most of RLD lymph came from the lung. Assuming body lymph Po2 equaled mixed venous Po2, they concluded  that  15% of TD lymph originated in the lung. Since TD flow greatly exceeded RLD flow, the net result was that about two thirds of pul­ monary lymph entered the thoracic duct both in normal and edematous conditions.

Unfortunately, both RLD and TD lymph have traversed lymph nodes and Mayerson (7) has shown that small molecules (molcular weight< 1,000) equilibrate completely during lymph node transit.

Because of the importance of lymph gas tension in the lung and elsewhere, wo have reassess­ ed the oxygen tension of pulmonary lymph obtained from four unanesthetized sheep with chronic lymph catheters. We devised an oxygen-impermeable, external catheter system and measured steady state Po2   repeatedly over several hours. Our finding is that the average Po2 of nearly pure lung lymph is very similar to that of mixed  venous blood. It is not related to the tissue Po2 at its source.

How to Cite:

Staub, N. & Schultz, E., (1974) “OXYGEN TENSION OF NEARLY PURE PULMONARY LYMPH IN UNANESTHETIZED SHEEP”, Lymphology 7(2), 96-100.