title: Effect of concentration on restriction and diffusion of albumin in the excised rat diaphragm.
abstract: In tissue samples of rat diaphragm mounted between two chambers, we measured the flow of albumin solution (0-5 g/dl) containing radioactive tracer (125)I-albumin in response to a driving pressure of 20 cmH(2)O. The ratio of the albumin concentration of the output solution to that of the input (sieving ratio, C(out)/C(in)) was measured from solution radioactivity. C(out)/C(in) increased monotonically from 0.5 with the flow of approximately 0 g/dl albumin solution (tracer) to 0.9 with the flow of 5 g/dl albumin solution. We modeled the tissue as a membrane subjected to flows of high Peclet No. with a reflection coefficient sigma = 1 - C(out)/C(in). Values of sigma decreased from 0.5 with Ringer solution to 0.1 with 5 g/dl albumin solution. Hydraulic conductivity measured with the flow of Ringer solution increased with the flow of 5 g/dl albumin solution. Wet-to-dry weight ratio and radioactivity of tissue samples immersed in 0.01-5 g/dl albumin solutions indicated a 40% increase in tissue water, associated with an albumin volume fraction of 0.3 measured at 0.5-2 h. The slower rate of albumin uptake occurring up to 20-30 h indicated intracellular diffusion that was equal with 1 and 5 g/dl albumin solution but reduced with a 0.01 g/dl albumin solution. The results suggest that interstitial pores increase in size in response to an increase in albumin concentration. We postulate a two-pore model made of intracellular pores that coalesce into a set of larger pores by osmotic flow.
authors.affiliation: Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506-0070, USA.
authors.forename: Sonja M
authors.initials: SM
authors.lastname: Moe
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lai-Fook
mesh_terms: D000199:Actins / Q000737:chemistry; D000418:Albumins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D003964:Diaphragm / Q000378:metabolism / Q000473:pathology*; D004058:Diffusion; D004305:Dose-Response Relationship, Drug; D006820:Hyaluronic Acid / Q000737:chemistry; D006821:Hyaluronoglucosaminidase / Q000378:metabolism; D009218:Myosins / Q000737:chemistry; D009924:Organ Culture Techniques; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013395:Sucrose / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000199:Actins; D000418:Albumins; D014867:Water; D013395:Sucrose; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase; D009218:Myosins