Maximal contractions to hydrogen peroxide (3 × 10−5 M) in rings without endothelium of femoral arteries from control and STZ-treated rats. Effect of catalase, deferoxamine, MnTMPyP, INDO, S18886 and SC19220 on the response. Data are expressed as percentage of the reference contraction to 60 mM KCl and are shown as means±s.e. mean; n=9. *Significant difference from the rings from control rats; #statistically significant difference from the rings from STZ-treated rats under control conditions (P<0.05). INDO, indomethacin; MnTMPyP, Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride; S18886, terutroban, (3-[(6-amino-(4-chlorobenzensulphonyl)-2-methyl-5,6,7,8-tetrahydronapht]-1-yl) propionic acid; SC19220, 2-acetylhydrazide 10 (11 H)-carboxylic acid 8-chloro-dibenz [b,f] [1,4] oxazepine-10 (11 H)-carboxylic acid; STZ, streptozotocin.