Fenoldopam, a dopaminergic (DA 1 ) agonist, has been known to induce arteritis in the splanchnic arteries in rats by intravenous infusion. The arteritis was characterized by medial necrosis, hemorrhage, and endothelial hyperplasia in the acute phase and subsequent inflammatory responses in the adventitia. In the present study, the hypertrophic endothelial cells were examined immunohistochemically and electronmicroscopically. Immunohistochemical examination revealed marked positive reactions of von Wilbrand factor (vWF) and factor VIII in the endothelial cells. Electronmicroscopically, the number of rough endoplasmic reticulum (rER) and the size of the nucleolus were increased. These results suggest that endothelial hypertrophy in the acute phase of fenoldopam-induced arteritis is associated with increased protein synthesis of vWF and factor VIII in response to medial necrosis and hemorrhage. (J Toxicol Pathol 2002; 15: 119-122)

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The common lipopolysaccharide (LPS)