Simultaneous study of capillary permeability to several macromolecules

Abstract

Capillary permeability to three exogenous macromolecules (dextran with mol. wt. of 250,000; albumin-I131 with mol. wt. of 69,000, and dextran-C14 with mol. wt. of 16,000) and endogenous serum proteins were studied simultaneously in dogs by following the transfer of these substances from plasma into the thoracic duct lymph. Two hours after the administration of the macromolecules the lymph-to-plasma ratio for dextran 250,000 averaged 0.33 (sem 0.061) and that for albumin-I131 averaged 0.50 (sem 0.039). The lymph-to-plasma ratio for dextran-C14 exceeded unity because of the rapid decline in plasma concentration and the slow transit of fluid to the collecting cannula. The data reported here provide a basis for studying changes in capillary permeability under abnormal conditions.