An exaggerated oxidative stress has been postulated as the link between
diabetes mellitus (D.M) and endothelial dysfunction. This study aimed to
investigate the possible therapeutic effect of chronic zinc administration (0.5% in
drinking water) on renal artery vascular reactivity and oxidative stress indices viz
serum oxidized to reduced glutathione ratio (GSH/GSSG), trolox equivalent
antioxidant capacity (TEAC) and lipohydroperoxides (LPO) in experimentallyinduced
D.M by streptozotocin (STZ) (60 mg/kg i.p single dose) in rats. Using
Doppler technique in this study indicated that chronic zinc administration
significantly (p<0.05) improved renal artery vascular reactivity to acetylcholine
(Ach). Such an effect which seemed to be mediated by two mechanisms: (1) Zinc
restored plasma antioxidant defenses as it significantly (p<0.05) increased the
GSH/GSSG ratio, the (TEAC) and significantly (p<0.05) decreased LPO. This
resulted in lowering the quenching effect of free radicals on nitric oxide (NO). (2)
Chronic zinc administration significantly (p<0.05) increased intracellular me+
concentration and significantly (p<0.05) decreased intracellular Ca2+ content, thus
protecting against oxidative cell damage and improving smooth vascular cell
relaxation respectively.
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