Plasma pharmacokinetics and interstitial diffusion of macromolecules in a capillary bed.
Concentration-time profiles of fluorescein isothiocyanate (FITC)-conjugated bovine serum albumin and a graded series of FITC-dextrans of 20,000-70,000 molecular weight were measured within the erythrocyte-free plasma layer in individual vessels and at various positions within the interstitial tissue space of mature granulation tissue grown in a rabbit ear chamber. Sodium fluorescein was used as a representative small molecule. The plasma pharmacokinetic data were found to follow a biexponential decay in time. A one-dimensional model of diffusion adequately described interstitial transport. Interstitial diffusion coefficients decreased progressively with Stokes-Einstein radius with values for albumin being significantly reduced from that for a dextran of equivalent hydrodynamic radius. Interstitial diffusion of sodium fluorescein and albumin agreed with a fiber-matrix model, whereas the interstitial diffusion of dextrans more closely corresponded to a pore model.
D002196:Capillaries / Q000502:physiology*; D003911:Dextrans / Q000097:blood*; D004058:Diffusion; D019793:Fluorescein; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives*; D005452:Fluoresceins / Q000097:blood*; D007700:Kinetics; D008297:Male; D008433:Mathematics; D008970:Molecular Weight; D012710:Serum Albumin, Bovine / Q000031:analogs & derivatives*; D013997:Time Factors
D003911:Dextrans; D005452:Fluoresceins; C039217:fluorescein isothiocyanate bovine serum albumin; C015219:fluorescein isothiocyanate dextran; D012710:Serum Albumin, Bovine; D016650:Fluorescein-5-isothiocyanate; D019793:Fluorescein