Alterations of the endothelial function of isolated aortae in rats with adjuvant arthritis.

Adjuvant arthritis was induced in 30 male Wistar rats by injection into the tail of heat-killed Mycobacterium butyricum. Three weeks later, 14 of these rats exhibited severe arthritic lesions. Their thoracic aortae were studied in parallel with those isolated from a control group. On rings precontracted with phenylephrine (0.1 microM), the endothelium-dependent relaxations produced by acetylcholine and histamine were significantly diminished in the arthritic group as compared to the control group. Moreover, the increase in tone induced by incubation with methylene blue (10 microM) (a nonspecific inhibitor of endothelium-derived relaxing factor) was significantly less pronounced in preparations isolated from the arthritic group. On the other hand, relaxations produced by the endothelium-independent vasodilators verapamil and nitroprusside were similar in both groups. It is concluded that adjuvant arthritis modifies the endothelium-derived relaxing factor-mediated responses of rat aorta.