MEASUREMENTS OF PLASMA GLUTAREDOXIN AND THIOREDOXIN IN HEALTHY-VOLUNTEERS AND DURING OPEN-HEART-SURGERY

Thioredoxin (Trx) and glutaredoxin (Grx) are both multifunctional redo x-active proteins. In this study, Grx was identified in human plasma b y immunoaffinity purification. The affinity-purified material from hum an plasma displayed a band of 12 kDa identical to recombinant human Gr x by Western blotting and its glutathione-dependent reducing activity of beta-hydroxyethyl disulfide. Competitive enzyme-linked immunosorben t assays (ELISA) showed that plasma levels (mean +/- SD) of Grx and Tr x in healthy volunteers (n = 41) were 456 +/- 254 ng/ml and 28.5 +/- 1 2.6 ng/ml, respectively. in cardiac surgical patients (n = 17), plasma Grx levels did not significantly change during cardiopulmonary bypass (CPB). In contrast, Trx levels in arterial plasma measured by sandwic h ELISA and corrected for hemolysis were elevated during reperfusion o f the postcardioplegic heart (p = .0001 at maximum), whereas by compet itive ELISA Trx increased during surgical preparation for CPB, but dec reased during CPB. When recombinant Trx was oxidized, immunoreactive T rx levels were decreased by competitive ELISA but not changed by sandw ich ELISA. These results suggest that oxidized Trx is released into pl asma during CPB. There was no significant difference in Trx and Grx le vels between arterial and intracoronarial plasma samples, indicating n o specific release by the postcardioplegic heart. Trx and Grx may be i mportant components in the plasma defense against oxidative stress. (C ) 1998 Elsevier Science Inc.