The exclusion of human serum albumin by human dermal collagenous fibres and within human dermis.

Preparations of dermal collagenous fibres and slices of human dermis have been equilibrated with 125I-labelled monomeric human serum albumin. The space inaccessible to the albumin in the fibres and in the dermis was determined by subtraction of the accessible space, calculated from the radioactivity of the specimen, from its total fluid. For a fibre preparation examined in detail, the fluid exclusion was independent of the concentration of either albumin or collagen. Binding of albumin to the fibres was not demonstrable. Three fibre preparations excluded albumin from 3.75 +/- 0.96, 3.55 +/- 0.67, and 2.05 +/- 0.39 g of fluid/g of collagen (+/-S.D.). Slices from three specimens of dermis excluded albumin from 1.45 +/- 0.08 g of fluid/g of insoluble solids or 1.57 +/- 0.11 g of fluid/g of collagen (+/-S.D.). Thus the exclusion of albumin by dermis was much less than expected from its content of collagenous fibres. On the basis of these data and the published composition of dermis, the concentration of albumin in the accessible interstitial space was estimated to be close to that in the plasma.