In vitro adsorption spectrum of plasma amino acids by coated charcoal hemoperfusion.

In order to clarify whether coated charcoal hemoperfusion is capable of normalizing amino acid disturbances in hepatic coma, in vitro adsorption and in vitro hemoperfusion studies were carried out. We have found that collodion-coated activated charcoal beads preferentially removed much more aromatic acids (AAA) than branched chain amino acids (BCAA). In the in vitro adsorption experiment with 50 microM amino acid standards aqueous solution, 99% of AAAs were removed by charcoal while only 50 to 81% of BCAAs were removed. As the concentration of amino acids in solution was doubled from microM to 100 microM, BCAA removal was halved while about 90% of AAA was still being removed. In vitro hemoperfusion with heparinized blood from hepatic failure rats, the clearance and the removal of AAAs were significantly greater than those of BCAAs. Consequently, the molar ratio of BCAA over AAA was markedly improved from the initial 1.09 to 3.87 after 60 min of hemoperfusion. Thus, we have demonstrated the preferential adsorption of aromatic amino acids by collodion-coated charcoal beads. The correction of BCAA/AAA molar ratio is also demonstrated.