Previous studies of oxygen-derived free radical generation based on spin-trapping methods have shown a signal formed of six bands (sextet) using electron spin resonance spectrometry (ESR) or coronary effluents collected during post-ischaemic reperfusion of isolated hearts perfused with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The origin of this signal has recently become controversial. In the present study we show that, in the rat, this sextet and cytosolic iron release occur simultaneously, and that this signal can be inhibited by the iron chelator desferrioxamine. It also appears that the iron release is not protein bound, and could therefore have a marked catalytic activity. This may be responsible for the production or an artefactural signal observed as the sextet.
