Arterial influx, efflux and tissue content of albumin in rabbits in vivo.
The uptake, in vivo, of 125I-labelled rabbit serum albumin by the thoracic intima-media of rabbits was determined at different times after single injection of the tracer. Plasma decay of radioactivity was monitored until sacrifice. Kinetic analysis of the plasma decay by a three compartment model gave the values of the fractional rates of catabolism and of transfers between intra- and two extravascular compartments. The uptake data were analysed by a similar compartmental model involving transfers between plasma and arterial tissue. kin, the fractional rate of influx into the tissue and kout, the fractional rate of efflux from the tissue were calculated by a procedure proposed earlier. The values of kin and kout (0.055 microliter X cm-2 X h-1 and 0.2 h-1), converted to proper units, are closer to the fractional rates for the slowly exchanging pool, probably representing tissues with non-fenestrated endothelium. On the basis of the model and a normal plasma level of albumin, it can be calculated that the steady state albumin content of intima-media should be about 11 micrograms X cm-2. Direct determination of arterial albumin content by electroimmunoassay gave a value consistent with this.
D000818:Animals; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D011817:Rabbits; D012711:Serum Albumin, Radio-Iodinated / Q000378:metabolism*; D013895:Thoracic Arteries / Q000378:metabolism*
D012711:Serum Albumin, Radio-Iodinated