Induction of mitochondrial dysfunction in patients under cardiopulmonary by-pass: preliminary results.

Cardiac surgery is often performed by cardiopulmonary by-pass (CPB), generally associated with organ dysfunction. The aim of this work was to determine if and how this phenomenon is related to mitochondrial damage. To this purpose, the effect of the addition of serum from CPB patients to human fibroblasts cultures on mitochondrial respiratory chain and oxidative phosphorylation (OXPHOS) activities was investigated. Serum samples of five patients were obtained before (pre-CPB) and after 6 h CPB weaning (CPB). Mitochondrial OXPHOS activities were examined by polarographic and spectrophotometric assays, and reactive oxygen species (ROS) production was measured by a spectrofluorimeter. Addition of CPB serum to fibroblasts determined a decrease of mitochondrial oxygen consumption due to an inhibition of mitochondrial respiratory chain and some OXPHOS enzymes activities. This inhibition seems to be mainly related to a reduced activity of complex I. Our data represent the first translational research evidence showing that CPB determines mitochondrial dysfunction which leads to impairment of OXPHOX activities and to an increase in ROS production, compromising tissue bioenergetic efficiency.