title: Microvascular exchange of albumin.
abstract: The transcapillary exchange of albumin was examined in seven rabbits using plasma disappearance curves and black box kinetic analysis. From the experimental data and the Renkin and Kedem-Katchalsky equations it was found that the average whole body diffusional capillary permeability coefficient for albumin was 24 X 10(-8) cm/sec as the total whole body capillary permeability-surface area product was 0.0739 ml/100 g X min (surface area estimate 50 cm2/g). The convective components of the net albumin tracer flux was found to be 15%, and the pure permeation ratio of influx to outflux (R = 0.61) of systemic albumin was reduced to 0.57. The solvent drag component of either unidirectional flux relative to the permeative component was 0.037. The Casley-Smith hypothesis of solvent drag convection up a gradient across the capillary membrane could not be verified as possible. It is emphasized that the so-called transcapillary escape rate is an arbitrary rate constant which cannot be attributed to reflect any physiological process, especially not the transcapillary exchange of albumin.
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D005260:Female; D007700:Kinetics; D009132:Muscles / Q000098:blood supply; D011817:Rabbits; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D012709:Serum Albumin