Abstract: | Extraction of whole lobes of normal rat liver with dimethyl sulphoxide (DMSO) under N2 gives extracts which contain 5—10 μmol/l·O?2 (50-100 nmol·O?2 per 10 ml extract per 4 g liver; 1.25-2.50 nmol·O?2 per millilitre per gram liver). Evidence for ·O?2 in the extracts is given by: (1) electron spin resonance signals (ESR), (2) differential pulse polarography (DPP), (3) chemiluminescence (CL), and (4) nitroblue tetrazolium reduction (NBT). All tests yield results identical with those obtained with authentic ·O?2. Extraction of ·O?2 is enhanced by tetrabutyl ammonium ion, and is maximal at 1-3 min. These results raise the possibility that substantial amounts of ·O?2 are normally sequestered in protective membranous sites in vivo. |