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Background & Objective: In this research, we study the simultaneous effects of Nitric Oxide (NO) and stress on prefrontal cortex of rats. Nitric Oxide is an unstable small molecule that involved in many physiological and pathological conditions. Brain’s prefrontal cortex has important role on personality and mental state. Its development continues after birth and this period is the most sensitive time for brain’s cortex to response to environmental parameters such as psychological stresses. Materials & Methods: In this study Wistar male rats received L-arginine (200 mg/kg) as NO precursor, L-NAME (20mg/kg) and 7-nitroindazole (25mg/kg) as non specific and specific NO sentries inhibitors. L-arginine and L-NAME were injected intra peritoneal (IP) and 7-nitroindazole injected subcutaneously (S.C) during one month per day. Rats divided in two groups (with stress and without stress). The kind of stress was immobilization every day for one month during injection of materials. Brains were removed after this period and each brain with a coronal section manner divided in two parts .Anterior part of brain fixed by formalin and tissue processing was done. By using rotatory microtome 10? serial cross sections were obtained and stained with H & E. Posterior part of brain homogenized with such solution then amount of NO in obtained solution was measured by spectrophotometer with 540 nm wavelength. Results: Statistical analysis of light microscopic findings indicated that stress of immobilization with use of L-NAME and 7-nitroindazole result in decrease of thickness of prefrontal cortex , numbers of Betz cells and NO production in rats’ brain, it means L-NAME and 7-nitroindazole exaggerate the brain damage and from other hands L-arginine with stress can convert these results. Conclusion: On the basis of these results we believe that stress of immobilization damages prefrontal cortex and also NOS inhibitors can aggravate the cortical damage. On the other hand although NO precursor (L-arginine) decreases the cortical damage in rats that impress with stress, it can result in these changes in rat’s brain without stress.

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Background and Objective: Nitric oxide synthase (NOS) paly a role in nitric oxide (NO) generation. Despite the beneficial effects of NO on different body systems its overproduction of produce reactive nitrogen species (RNS) and nitrosilation of proteins. This study was done to evaluate the effect of asymmetric dimethylarginine (ADMA) and NG-Monomethyl-L-arginine methyl ester (L-NMMA) on inhibition of nitric oxide synthase activity. Materials and Methods: In this laboratory study, Nitric oxide synthase was extracted from 500 grams of sheep kidney by homogenization, ammonium sulphate precipitation and column chromatography on DEAE-32 Cellulose and 2', 5'-ADP-agarose. During purification, protein content was measured according to the Bradford and enzyme activity was assayed using the Griess reactions the inhibitory effects of 25 μΜ concentrations of ADMA and L-NMMA on purified enzyme were determined. Results: Specific activity and yield of NOS were 0.6 units/mg protein and 0.9%, respectively. Molecular weight of purified enzyme was 54 KD with SDS-PAGE. ADMA and L-NMMA in 25 μΜ concentrations reduced enzyme activity by 76 and 61.2%, respectively. Km values for NOS in absence and in presence of ADMA and L-NMMA were 5.32 μM, 31.25 μM (P<0.05) and 14.29 μM (P<0.05), respectively. Vmax for NOS in absence and presence of inhibitors was not changed. Conclusion: ADMA and L-NMMA have competitive inhibitory effect on NOS activity and ADMA have higher inhibitory effect than L-NMMA.

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Background and Objective: The most important factor in the integrity of saphenous vein is the health degree of endothelium which guaranties the dilation of them after cronary bypass sergery. Kind of preservative soulution has a key role in endothelial protection. This study was done to evaluate Protective effect of perserved solutions of krebs contains verapamil, adrenaline and propranololol in comparision with Krebs and Heparinated blood on desqumation of the endothelial cell in Saphenous vein of Guinea pig.
Methods: This experimental study was done on 28 male Guinea pigs with 380±40g weight.for separating 3mm of saphenous vein rings and Measuring of rings nitric oxide released in preserving solutions: Krebs (K), Krebs plus propranolol (K+P), adrenaline (K+A) and verapamil (K+V) compaired with heparinized blood at 30, 45, 60 and 90 minutes after harvesting measured by micro plate Griess reaction. Rings also stained by H&E and examined by light microscopy to evaluate endothelial desqumation.
Results: Average concentration of nitric oxide (NO) in the Krebs plus Verapamil solution (K+V) Vs Heparinized Blood (HB), Krebs (K), Krebs plus Adrenaline (K+A) and Krebs plus Propanololol (K+P) revealed significant increase in NO release (P<0.05). The maximum NO measurement was 45 minuts after harvesting. Also histological study with H&E staining showed that endothelial layer was intact only in Krebs plus verapamil in compaired to control group, but in the other solutions the vascular intimal cells had suffered different degrees.
Conclusion: It seems that Krebs solutions containing verapamil has more efficiently to the proper functioning of the saphenous veins endothelium in animal modle.