BackgroundHyperoxia is shown to impair airway relaxation via limiting L-arginine bioavailability to nitric oxide synthase (NOS) and reducing NO production as a consequence. L-arginine can also be synthesized by L-citrulline recycling. The role of L-citrulline supplementation was investigated in the reversing of hyperoxia-induced impaired relaxation of rat tracheal smooth muscle (TSM).MethodsElectrical field stimulation (EFS, 2–20 V)-induced relaxation was measured under in vitro conditions in preconstricted tracheal preparations obtained from 12 day old rat pups exposed to room air or hyperoxia (>95% oxygen) for 7 days supplemented with L-citrulline or saline (in vitro or in vivo). The role of the L-citrulline/L-arginine cycle under basal conditions was studied by incubation of preparations in the presence of argininosuccinate synthase (ASS) inhibitor [α-methyl-D, L-aspartate, 1 mM] or argininosuccinate lyase inhibitor (ASL) succinate (1 mM) and/or NOS inhibitor [Nω-nitro-L-arginine methyl ester; 100 μM] with respect to the presence or absence of L-citrulline (2 mM).ResultsHyperoxia impaired the EFS-induced relaxation of TSM as compared to room air control (p < 0.001; 0.5 ± 0.1% at 2 V to 50.6 ± 5.7% at 20 V in hyperoxic group: 0.7 ± 0.2 at 2 V to 80.0 ± 5.6% at 20 V in room air group). Inhibition of ASS or ASL, and L-citrulline supplementation did not affect relaxation responses under basal conditions. However, inhibition of NOS significantly reduced relaxation responses (p < 0.001), which were restored to control level by L-citrulline. L-citrulline supplementation in vivo and in vitro also reversed the hyperoxia-impaired relaxation. The differences were significant (p <0.001; 0.8 ± 0.3% at 2 V to 47.1 ± 4.1% at 20 V without L-citrulline; 0.9 ± 0.3% at 2 V to 68.2 ± 4.8% at 20 V with L-citrulline). Inhibition of ASS or ASL prevented this effect of L-citrulline.ConclusionThe results indicate the presence of an L-citrulline/L-arginine cycle in the airways of rat pups. L-citrulline recycling does not play a major role under basal conditions in airways, but it has an important role under conditions of substrate limitations to NOS as a source of L-arginine, and L-citrulline supplementation reverses the impaired relaxation of airways under hyperoxic conditions.

Contamination of soil and water by various heavy metals such as Cd, Pb, Ni, Cu, and Fe is increasing day by day as a result of different activities, such as industrialization and urbanization. Lead (Pb), Cadmium (Cd), and Nickel (Ni) are examples of potential heavy metals that are neither essential elements nor have any role in the process of cell metabolism, but are easily absorbed and accumulated in different parts of a plant and living beings. This study was to investigate the translocation and bioaccumulation of heavy metals such as Pb, Ni, Cd, Cu, and Fe in Urtica dionica L and soil samples from 2 sites (uncontaminated-Koliq and contaminated-Kishnica in the Republic of Kosovo). The results revealed that in the contaminated site, the mean level of all the metals in soil and different parts (root, stalk, and leaf) of the plant were found to be significantly (p<0.01) higher than the uncontaminated site. Multivariate analysis was used to determine the distribution of metals within the study area. The trace metal contents from different parts of these plants were determined by the use of AAS. The results revealed that Urtica dionica L. translocated high amounts of metals to its organs, especially to leaves, so that translocation factors were much higher than one (>1). However, these concentrations of heavy metals in the soil and Urtica dionica L were higher than levels specified according to the standards in UK and Germany.

Heavy metals are naturally occurring elements on the earth's crust and they are also referred to as trace elements [1]. Some of these metals have found application in many areas of human life, such as agriculture, pharmacy, cosmetics, industry, medicine, etc. Human exploitation of these metals has increased the risk of environmental pollution from them. In view of their toxic properties they can be dangerous to all receiving ecosystems [2]. Sources of heavy metals contamination of aquatic ecosystems can be mines, industrial wastewater, fertilizers, pesticides and also deposition and erosion of the geological matrix [3]. Contamination of water with these pollutants can have

The aim of the current investigation is to evaluate the impact of water quality in hematological and biochemical blood profile in two habitats of common carp (Cyprinus carpio) captured in Batllava and in Radoniqi Lake. It has been found that Radoniqi Lake is characterized with increased levels of physicochemical parameters (T, DO, PO 4-3 , NO 3-N, NO 2-N). In Radoniqi Lake were recorded also heavy metal content such as Cd, Pb, Ni and Cu while in Batllava Lake only presence of Cu was recorded. Given the developed agriculture in the region where Radoniqi Lake is located, increased level of PO 4-3 , Cd and Cu can be attributed to agricultural pollution. Blood is taken for hematological (RBC, Hgb, MCV, MCH, MCHC, WBC), and biochemical (ALP, AST, ALT, Glucose, Cholesterol, Triglyceride, Total lipid, Total protein) analysis from twenty fish of each lake. The results of hematological parameters show that there is a difference between investigated fishes of respective lakes. There are slight differences in the values of Hgb, MCHC and WBC, while the changes are significant in RBC, MCV and MCH. By contrast, the biochemical parameters have shown significant differences, with the exception of the amount of cholesterol, where the differences are insignificant. Given the water quality of the two lakes, the results of this research show that water quality affects the health condition of fish. The high values of hematological and biochemical parameters in the fish of Radoniqi Lake are indicative that these fish suffer from stress caused by water pollution with heavy metals.

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