The present study was conducted to dissect the underlying mechanisms by which catecholamines protect cells against preservation injury. To this end, we firstly defined the cellular and molecular differences between protected and nonprotected cells and secondly defined the mediators that were involved in cold-induced damage. Cold storage of untreated human umbilical vein endothelial cells (HUVECs) resulted in profound cellular damage as assessed by lactate dehydrogenase (LDH) release and by morphological changes, e.g. cell size alterations and loss of cytoskeletal organization. Treatment of HUVECs with catecholamines before cold storage prevented cellular damage in a dose- and time-dependent fashion. Similar results were obtained with carvedilol or its hydroxylated derivative BM91.0228. Protection was not receptor-mediated and did not require de novo protein synthesis. The onset of protection occurred relatively quickly and the duration was long lasting. Addition of superoxide dismutase (SOD) to untreated HUVECs during cold preservation also was protective. Oxidation of catecholamines completely abrogated the protective effect of these compounds on cold-induced damage. Both at 4 degrees and 37 degrees C, catecholamines reduced the amount of reactive oxygen species (ROS) produced by HUVECs. In conclusion we have demonstrated that catecholamines protect cells against preservation injury either by scavenging of ROS or by inhibition of ROS production.