FREE-RADICAL GENERATORS CAUSE CHANGES IN ENDOTHELIAL AND INDUCIBLE NITRIC-OXIDE SYNTHASES AND ENDOTHELIN-1 IMMUNOREACTIVITY IN ENDOTHELIAL-CELLS FROM HYPERLIPIDEMIC RABBITS

Reactive oxygen species (ROS) play an important role in the damage of vascular endothelium during atherogenesis and impaired endothelium-dep endent vasorelaxation, We have studied the effect of two ROS generator s (H2O2 and menadione) and one of the most potent antioxidants (morin) on the double immunofluorescent staining of endothelial cells (EC) fr om both Watanabe Heritable Hyperlipidemic (WHHL) and New Zealand White (NZW) rabbits in primary cultures using antibodies against endothelin -1 (ET-1), endothelial (eNOS), and inducible nitric oxide synthase (iN OS). In aortic EC from normal rabbits, ROS decreased the immunoreactiv ity of eNOS and ET-1 and this effect was significantly reversed by mor in. In atherosclerotic rabbits, ROS had the same effect on the immunor eactivity of eNOS and ET-1 but also induced the expression of iNOS imm unoreactivity. In general, the cells from WHHL rabbits were less sensi tive to the protective effects of morin and more sensitive to the effe cts of ROS. It thus appears that the protective effect of morin may be due to neutralization of ROS and may be considered for the treatment of early stages of atherosclerosis, before macroscopic lesions have oc curred. (C) 1998 Academic Press.