A theory for the quantification of transcapillary exchange by tracer-dilution curves

Abstract

A mathematical formulation of the simultaneously obtained indicator-dilution curves of two tracers: one confined to plasma and another diffusible through the capillary barrier, is made. The procedure allows the estimation for the permeable substance of the fractional extraction from the blood, and the interstitial fractional turnover rate and compartment size. The experimental data is obtained in 3–4 min in isolated perfused organs. Na²² (NaCl) and siderophilin-Fe⁵⁹ first circulation dilution curves obtained in the isolated dog heart are used to exemplify the procedure.