Exchange transfusion with albumin-heme as an artificial O2-infusion into anesthetized rats: physiological responses, O2-delivery, and reduction of the oxidized hemin sites by red blood cells.

Human serum albumin (HSA) incorporating synthetic hemes, the tetrakis(o-pivalamido)phenylporphinatoiron(II) derivative (FeP), is an artificial hemoprotein (HSA-FeP) which is able to reversibly bind and release dioxygen under physiological conditions (in aqueous media, pH 7.4, 37 °C) like hemoglobin and myoglobin. Physiological responses to exchange transfusion with HSA-FeP solution [[HSA], 5 g/dL; FeP/HSA, 4 (mol/mol)] into rats after hemodilution and hemorrhage (Hct, about 10%) has been evaluated. The declined mean arterial pressure (MAP) and blood flow after a 70% exchange with HSA and the further 40% bleeding of blood were significantly recovered up to about 90% of the baseline values by the injection of HSA-FeP. Furthermore, the renal cortical O2-tensions and skeletal tissue O2-tensions were also increased, indicating the in vivo O2-delivery of HSA-FeP. Autoxidation of ferrous Fe(II)P to ferric Fe(III)P was retarded in the blood stream; the half-lifetime of the dioxygenated FeP [τ1/2(O2)] in vivo was ...