Chronic zinc administration improves endothelial cell function and vascular reactivity in experimentally induced diabetes mellitus in rats

ABSTRACT

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 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 [1] Zinc restored plasma antioxidant defenses as it significantly [p<0.05] increased the GSH/GSSG ratio, the [TEAC] and significantly [Sp<0,05] decreased LPO. This resulted in lowering the quenching effect of free radicals on nitric oxide [NO] [2] Chronic zinc administrarion significantly [p<0.05] increased intracelular Mg 2+ concentration and significantly [p<0.05] decreased intracellular Ca 2+ content, thus protecting against oxidative cell damage and improving smooth vascular cell relaxation respectively