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YALÇIN, AHMET SUHA

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Author: HAKLAR, GONCAGÜL × Subject: chemiluminescence ×

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    Oxygen radicals and nitric oxide in rat mesenteric ischaemia-reperfusion: Modulation by L-arginine and N-G-nitro-L-arginine methyl ester
    (WILEY, 1998) YALÇIN, AHMET SUHA; Haklar, G; Ulukaya-Durakbasa, C; Yuksel, M; Dagli, T; Yalcin, AS
    1. The aims of the present study were to detect changes in superoxide anion (O-2(.-)), nitric oxide (NO) and other reactive oxygen species (ROS) directly by measurement of chemiluminescence (CL) and to investigate the role of L-arginine, a nitric oxide synthase (NOS) substrate, and N-G-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, together with their molecular enantiomers D-arginine and D-NAME, in a rat mesenteric ischaemia-reperfusion (I/R) model. 2, Seventy-nine female Wistar albino rats were divided into eight groups, The first three groups underwent sham operation; group 1 was the control group, group 2 received L-arginine and group 3 received L-NAME. Ischaemia was produced in the remaining five groups by ligation of the superior mesenteric artery for 30 min followed by 60 min reperfusion, Group 4 rats were control I/R rats and groups 5-8 received either L-arginine, L-NAME, D-arginine or D-NAME, respectively. 3, Both luminol and lucigenin CL was significantly increased in I/R groups compared with sham-operated groups. L-Arginine significantly reduced CL measurements. D-Arginine was also protective, but not as much as L-arginine. Both L- and D-arginine had in vitro O-2(.-)-scavenging potential, as tested by the xanthine-xanthine oxidase system. N-G-Nitro-L-arginine methyl ester decreased lipid peroxidation values in addition to reducing CL measurements. Nitric oxide concentrations were significantly increased in VR groups in comparison with sham-operated groups. Peroxynitrite formation was increased by I/R. Treatment with L-NAME was beneficial by reducing NO concentrations in the reperfused ileum, 4, In our I/R model, O-2(.-), NO and other ROS were increased. Although NOS inhibitors were effective in reducing oxidative damage, increasing NO concentrations with L-arginine was also beneficial, presumably due to the ability of L-arginine to inhibit phagocyte adherence and its radical scavenging potential. In fact, NO may have different effects in terms of tissue injury or protection depending on the concentration of oxygen and the haemodynamic state of the tissue.
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    Measurement of reactive oxygen species by chemiluminescence in diet-induced atherosclerosis: protective roles of vitamin E and probucol on different radical species
    (SPRINGER, 1998) YALÇIN, AHMET SUHA; Haklar, G; Sirikci, O; Ozer, NK; Yalcin, AS
    We have investigated the effects of a high-cholesterol diet on the production of different reactive oxygen species in rabbit aortic rings and evaluated the protective effects of vitamin E and probucol in preventing peroxidative changes. Twenty-five male albino rabbits were divided into five groups. Control rabbits were fed a vitamin E-poor rabbit chow. Rabbits in the second group were given a vitamin E-poor diet supplemented with 2% cholesterol. Other groups received either 50 mg/kg vitamin E, 1% probucol, or both, in addition to 2% cholesterol for 4 weeks. Reactive oxygen species formation in aortic rings was measured by enhanced chemiluminescence using luminol and lucigenin. (The results were given as cpm/mg wet weight.) Further differentiation of radical species involved in luminol-enhanced chemiluminescence was performed using sodium azide and L-nitroarginine, a selective inhibitor of nitric oxide production. Our results indicated that cholesterol feeding increased lucigenin and luminol chemiluminescence, where the contribution of free radicals inhibited by sodium azide (radicals originating from endothelial cells or from phagocytes) were 53% and peroxynitrite 24%. Both vitamin E and probucol were effective as scavengers of free radicals, but the effect of vitamin E was more pronounced. In conclusion, the present study demonstrated excessive generation of reactive oxygen species within the atherosclerotic vessel. Peroxidative changes could be prevented by vitamin E and probucol treatment, but vitamin E seemed to be more efficient.