ritonavir and 3-nitrotyrosine

In THP-1 monocytes, cellular proteasome inhibition by ritonavir or ALLN is associated with increased production of oxidative stress. Both compounds produced comparable amounts of oxidative stress; however, normalization by alpha-tocopherol occurred solely after inhibition by ritonavir, and not by ALLN. Similar to that, alpha-tocopherol could normalize the reduced formation of 3-nitrotyrosine-modified proteins only after ritonavir treatment. In the absence of any proteasome inhibitor, intrinsic cellular proteasome activity was not modulated by alpha-, beta-, and gamma-tocopherols; however, delta-tocopherol, alpha-tocotrienol, and alpha-tocopheryl phosphate could significantly inhibit cellular proteasome activity and increased the level of p27(Kip1) and p53. Since oxidative stress was reduced by alpha-tocopherol only after proteasome inhibition by ritonavir and not by ALLN, it is concluded that, in this experimental system, alpha-tocopherol does not act as an antioxidant but interferes with the inhibitory effect of ritonavir.

Topics: Cell Line; Cyclin-Dependent Kinase Inhibitor p27; Humans; Intracellular Signaling Peptides and Proteins; Leupeptins; Monocytes; Oxidative Stress; Protease Inhibitors; Proteasome Endopeptidase Complex; Ritonavir; Tocopherols; Tocotrienols; Tumor Suppressor Protein p53; Tyrosine; Vitamin E

Although HIV Protease inhibitors significantly reduce the viral load, they are associated with increased risk of cardiovascular disease. The aim of this study was to investigate the effects of HIV protease inhibitor ritonavir on vascular endothelial cell function.. Porcine carotid arteries were perfusion-cultured for 24 h as controls or with 15 microM of ritonavir. Vessels were precontracted with norepinephrine followed by endothelium-dependent vasorelaxation with acetylcholine. Rings of vessels were cultured as controls or with ritonavir for 24 h and basal and NADPH-stimulated superoxide levels were determined using lucigenin-enhanced chemiluminescence. Superoxide levels in situ were also examined using dihydroethidium (DHE) staining, and nitrotyrosine levels were examined using a nitrotyrosine antibody.. Endothelium-dependent vasorelaxation was significantly reduced in ritonavir-treated vessels compared to controls. There were significant increases in basal and NADPH-stimulated superoxide production in vessel rings treated with ritonavir compared to control vessels. Dihydroethidium staining and nitrotyrosine staining were also elevated in endothelial cells of ritonavir-treated vessels, indicating increased superoxide production and increased oxidative stress, respectively, in ritonavir-treated vessels compared to controls.. These data demonstrate that HIV protease inhibitor ritonavir causes a significant reduction in endothelium-dependent vasorelaxation in cultured porcine carotid arteries. Increased oxidative stress may be a possible mechanism of HIV protease inhibitor ritonavir-induced endothelial dysfunction.

Topics: Animals; Arteries; Endothelial Cells; Endothelium, Vascular; Female; HIV Protease Inhibitors; In Vitro Techniques; Luminescent Measurements; Male; Oxidative Stress; Perfusion; Ritonavir; Superoxides; Swine; Tyrosine; Vasodilation