Figure 1.

Localization of O₂⁻-generating activity in rabbit aorta. Cross-sections of a rabbit aorta were treated with the superoxide dismutase inhibitor diethyldithiocarbamate (10 mM, A) or diethyldithiocarbamate with Tiron (10 mM, B) for 30 min, followed by 90 min with nitroblue tetrazolium (100 μM). The aortic rings were then fixed, imbedded in paraffin, and photographed. Distribution of blue formazan deposits indicates the primary source of aortic O₂⁻ is the adventitia. Magnification, 28×.