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
(120) in experimentally-induced 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: (I) Zinc restored
plasma antioxidant defenses as it significantly (p<0.05)
increased the GSH/GSSG ratio. the (TEAC) and significantly
(pc0.05) 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 Mg2+ concentration and significantly (p<0.05) decreased
intracellular Ca2" content, thus protecting against oxidative
cell damage and improving smooth vascular cell relaxation
respectively. |
