Effects of acute cold exposure (at I degrees C and 5 degrees C) on tissue redox state and oxidative stress parameters, as well as the onset of hypoxic signaling were investigated in the North Sea eelpout, Zoarces viviparus. Activation of the transcription factor HIF-1 (hypoxia inducible factor) was detected in liver samples after acute cold exposure. At this temperature the cellular redox milieu was significantly reduced (below -270 mV) as compared to controls (-250 to -267 mV). Increased levels of oxidative stress parameters (TBARS and protein carbonyls) were observed mainly during recovery at control temperature (12 degrees C). This increase in oxidative stress parameters, in spite of maintained antioxidant capacity, indicates that acute cold stress and recovery mimic ischemia/reperfusion events as found in mammals. Notably the non-enzymatic antioxidant defense (e.g. glutathione) may play an important role for eelpout ROS scavenging capacity under cold stress. (c) 2006 Elsevier Inc. All rights reserved.