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Role of albumin arginyl sites in albumin‐induced reduction of endothelial hydraulic conductivity
Author(s) -
Powers Michael R.,
Blumenstock Frank A.,
Cooper Jeffrey A.,
Malik Asrar B.
Publication year - 1989
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041410314
Subject(s) - albumin , chemistry , chromatography , serum albumin , hydrostatic pressure , biochemistry , physics , thermodynamics
We determined the effect of albumin on endothelial hydraulic conductivity (L p ) and the contributions of the positively charged arginyl and lysinyl residues of albumin in mediaing the effect. Studies were made using monolayers of cultured sheep pulmonary artery endothelial cells grown to confluence on polycarbonate filters. Water flux was measured as transendothelial hydrostatic pressure was varied from 5 to 20 cm H 2 O. L p was calculated from the slope of the relationship of water flux versus pressure. The L p of endothelial monolayers perfused with albumin‐free Hanks Balanced Salt Solution (HBSS) was compared to perfusion with HBSS containing either native albumin, or albumin in which the arginyl residues were modified by a condensation reaction with 1,2‐cyclohexanedione (CHD‐albumin), or albumin in which the lysinyl residues were modified by a substitution reaction with succinic anhydride (SC‐albumin). Baseline L p at 2.5 mg/ml native albumin was 1.6±0.1 × 10 −6 cm/s/cm H 2 O compared to the filter L p after removing cells of 3.0 ± 0.3 × 10 −4 cm/s/cm H 2 O. Endothelial L p increased by 60% when albumin concentration was decreased from 2.5 mg/ml to 0.5 mg/ml ( P < 0.05), but did not change with an increase in concentration to 10 mg/ml. Albumin‐free buffer and CHD‐albumin increased endothelial L p by 2.2 ± 0.3‐fold and 1.9 ± 0.3‐fold, respectively ( P <0.05). All endothelial L p values were restored to baseline when the native albumin concentration was returned to 2.5 mg/ml. Excess l‐arginine (2 × 10 −3 M) inhibited the effect of native albumin and increased endothelial L p 1.5 ± 0.02‐fold ( P <0.05), but excess l‐lysine (4 × 10 −3 ) in the presence of native albumin had no effect on L p . None of the perfusates altered the filter L p value. Neutral dextran (70 kD), in contrast to native albumin, had no effect on endothelial L p . These results indicate that albumin reduces the hydraulic conductivity of endothelial monolayers in a concentration‐dependent fashion and that the arginyl residues of albumin are required for the response. The effect of albumin may be meditated by a charge interaction of albumin with the endo‐thelium.