Effect of Acute and Chronic N (omega)-nitro-L-arginine Administration on Plasma Nitrite/Nitrate and Malondialdehyde Levels in Rats

Abstract

Objective: The aim of this study was to investigate the effects of acute and chronic administrations of Nw nitro-L-arginine (L-NNA), a non-spesific NOS inhibitor, on plasma levels of Nitrite/Nitrate (NOx) and Malondialdehyde (MDA) in rats. Material and Method: A single dose L-NNA (aL-NNA, 25mg/kg i.p.) was administered and systolic blood pessure (SBP), NOx were measured at 1, 3, 24 hours. MDA were measured at 1, 24 hours. L-NNA was administered orally dose of 15mg/100ml/day (d-LNNA) and 45mg/100ml/day (yLNNA) for 2 weeks. dL-NNA was divided into 3 subgroups: SBP, NOx and MDA levels were determined at the end of experiments in dL-NNA0 subgroup and also 24 (dL-NNA24) and 48 hours (dL-NNA48) after the cessation of chronic L-NNA administration. yL-NNA group was not divided subgroups. Results: In the aL-NNA, SBP was higher at first and third hour which declined to the basal values at 24th hour. NOx was not change at one hour but decreased at third hour and returned to the basal levels at 24th hour. MDA were higher at first hour and remained high at 24th hour. In the long term L-NNA treated groups; both doses of L-NNA caused significant increase in SBP but NOx levels were increased only in the yL-NNA. MDA levels of dL-NNA0 were not changed but there was a significant increase in the MDA levels of the dL-NNA24, dL-NNA48 and yL-NNA. Conclusion: Results from this study indicates that acute L-NNA application causes oxidative stress but its chronic applications caused the same effect only at high doses. ©2008, Fırat University, Medical Faculty

Keywords

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Akut ve Kronik N (omega)-nitro-L-arjinin Uygulamalarının Sıçanlarda Plazma Nitrit/Nitrat ve Malondialdehit Düzeylerine Etkileri

Öz

Amaç: Bu çalışmada, sıçanlarda non-spesifik NOS inhibitörü Nw nitro-L-arjinin'in (L-NNA) akut ve kronik uygulamalarının, plazma Nitrit/Nitrat (NOx) ve Malondialdehit (MDA) düzeylerine etkilerinin araştırılması hedeflendi. Gereç ve Yöntem: Sıçanlara tek doz L-NNA (Grup aL-NNA, n=19, 25mg/kg i.p.) uygulandı; bu ana grup 3 alt gruba ayrılarak sırasıyla 1 (Grup aLNNA1, n=4), 3 (Grup aL-NNA3, n=9 ) ve 24 (Grup aL-NNA24, n=6) saat sonra sistolik kan basıncı (SKB) ve plazma NOx ölçümleri yapıldı. MDA ölçümleri ise 1. ve 24. saatlerde yapıldı. Bir diğer seri deneyde, sıçanlara iki hafta süreyle L-NNA içme suyunda iki farklı konsantrasyonda (sırasıyla, Grup dL-NNA, ≈15mg/100ml, n=19 ve Grup yL-NNA, ≈45mg/100ml, n=28) uygulandı. dL-NNA grubu 3 alt gruba ayrıldı: bir altgrupta L-NNA uygulamasının durdurulmasından hemen sonra (Grup dL-NNA0, n=7), diğerlerinde ise L-NNA uygulamasının durdurulmasından 24 (Grup dLNNA24, n=6) ve 48 (Grup dL-NNA48, n=6) saat sonra SKB, plazma NOx ve MDA düzeyleri ölçüldü. Grup yL-NNA ise altgruplara ayrılmadı. Bulgular: aL-NNA grubunda SKB 1. ve 3. saatlerde yükselirken 24.saatte bazal değerlere geri döndü. Bu grupta plazma NOx değerleri 3. saatte düştü fakat 24. saatte normale döndü, plazma MDA değerleri ise 1. saatten itibaren anlamlı şekilde yükseldi. dL-NNA0 alt grubunda deney sonunda plazma NOx ve MDA düzeyleri değişmezken dL-NNA24 ve dL-NNA48 altguplarında MDA yükseldi. yL-NNA grubunda ise hem plazma NOx hem de MDA düzeyleri yüksekti. Sonuç: Bu sonuçlar tek doz L-NNA uygulamasının oksidatif strese neden olduğunu, ancak kronik uygulamalarda oksidatif stresin sadece yüksek konsantrasyonlarda oluştuğunu göstermektedir. ©2008, Fırat Üniversitesi, Tıp Fakültesi

Anahtar Kelimeler

• Kan Basıncı, NO Sentaz, Malondialdehit, Sıçan

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17. Kabul Tarihi: 03.12.2007