Ascorbate prevents the interaction of superoxide and nitric oxide only at very high physiological concentrations.

نویسندگان

  • T S Jackson
  • A Xu
  • J A Vita
  • J F Keaney
چکیده

The bioactivity of nitric oxide (.NO) depends, in part, on its interaction with superoxide. Usually, superoxide dismutase (SOD) preserves .NO bioactivity by limiting the availability of superoxide. Ascorbic acid also effectively scavenges superoxide, but the extent to which this interaction is necessary for intact .NO bioactivity is not known. Therefore, the present study examined the effect of ascorbic acid on .NO bioactivity with isolated rabbit arterial segments. A steady flux of superoxide (1.15 to 2.3 micromol . L-1 . min-1) produced either by pyrogallol autoxidation or a hypoxanthine/xanthine oxidase system inhibited endothelium-derived .NO-mediated arterial relaxation elicited by acetylcholine. This effect of superoxide was completely blocked by SOD (300 IU/mL) and the manganese SOD mimic EUK-8 (300 micromol/L) and partially inhibited by ascorbic acid (10 mmol/L). Lower concentrations of ascorbic acid were ineffective despite scavenging >90% of superoxide. We increased the endogenous flux of superoxide (3.2+/-0.3-fold) by inhibiting vascular copper-zinc SOD with diethyldithiocarbamate. This increased endogenous flux of superoxide produced an impairment of .NO-mediated arterial relaxation that was reversed by EUK-8 (300 micromol/L) but not ascorbic acid (10 mmol/L) despite equivalent scavenging of the endogenous superoxide flux. We used 3-nitrotyrosine formation (from peroxynitrite) as an indicator of .NO interaction with superoxide and found that SOD and EUK-8 compete more effectively with .NO for superoxide than does ascorbic acid. These data indicate that preservation of .NO bioactivity by superoxide scavengers depends not only on superoxide scavenging activity, but also on the rate of superoxide scavenging. Normal extracellular concentrations of ascorbic acid (30 to 150 micromol/L) are not likely to prevent the interaction of .NO with superoxide under physiological conditions.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Effects of Exogenous Nitric Oxide on Germination and Physiological Properties of Basil under Salinity Stress

Nitric oxide (NO) is a bioactive molecule, which was found to have several physiological roles, including antioxidant. To have a better understanding of the effects of NO concentrations (0, 0.1 and 0.2 mM) on germination, growth, photosynthetic pigments, lipid peroxidation and antioxidant activity of basil (Ocimum basilicum L.) under different salinity concentrations (0, 100 and 200 mM of NaCl)...

متن کامل

Effects of Copper Heavy Metal and Interaction With Nitric Oxide on Growth Parameters, Photosynthetic Pigment, Soluble Carbohydrate Content and Antioxidant Enzymes in Portulaca oleracea L. Ferdous Fendereski, Mahlagha Ghorbanli* and Arian Sateei

Copper is one of the heavy metal in plant that causes toxicity at high concentration via producing reactive oxygen species. Nitric oxide can protect cells from oxidative stress produce by reactive oxygen species. Effect of different concentrations of copper (1000, 1500 and 2000 μM) and interaction with nitric oxide (100 and 150 μM) were studied on growth parameters (shoot and root length) and s...

متن کامل

Effect of different concentrations of Zinc and their interaction with Sodium nitroprusside (SNP) on physiological and biochemical parameters of Plantago major L. Sara Nasiri Savadkoohi1*, Sakineh Saeidi-sar2 Abbas Ali Dehpour3 and Hossein Abbaspour1

Zinc is a necessary micronutrient in plants whose deficiency can alter essential functions in plant metabolism. High concentrations of Zn can be potentially toxic to plants causing phytotoxicity by the formation of reactive oxygen species. On the other hand, sodium nitroprusside (SNP), a donor of nitric oxide (NO) can protect cells from oxidative damage produce by reactive oxygen species. In th...

متن کامل

اثر اسانس آویشن شیرازی بر تولید یون سوپراکسید و نیتریک اکسید و بیان ژن‌های NADH اکسیداز و نیتریک اکسید سنتاز در سلول‌های ماکروفاژ

Objective: In this study, inhibitory effect of Zataria multiflora essential oil on superoxide and nitric oxide production and NADH oxidase (NOX) and nitric oxide synthase (NOS) expression was examined. Materials and Methods: Zataria essential oil was obtained by hydro-distillation and chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). Superoxide and ni...

متن کامل

The effect of arsenic and sodium nitroprusside on the physiological responses and antioxidant enzymes activity of Isatis cappadocica

Arsenic (As) stress, through the creation of oxidative stress, can cause phytotoxicity (e.g. The decrease of growth and chlorophyll content) in plants. Nitric oxide (NO), by promotion of the antioxidant system, plays an important role in reducing heavy metal-induced oxidative stress. In this study, the role of exogenously applied sodium nitroprusside (SNP; a NO donor) on physiological responses...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Circulation research

دوره 83 9  شماره 

صفحات  -

تاریخ انتشار 1998