11
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Presence of bilitranslocase in the vascular system and its role in the vasodilatation activity of anthocyanins

      abstract
      1 , , 1 , 2 , 1 , 3
      BMC Pharmacology
      BioMed Central
      15th Scientific Symposium of the Austrian Pharmacological Society (APHAR) Joint meeting with the Hungarian Society of Experimental and Clinical Pharmacology (MFT) and the Slovenian Pharmacological Society (SDF)
      19–21 November 2009

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background Flavonoids are well known for their vasodilatation activity. Their mechanism of action is still to be elucidated. Bilitranslocase is a bilirubin-specific membrane carrier that is also responsible for the ATP-independent transport of flavonoids across the cell membrane [1]. Recently, the expression of bilitranslocase in the endothelium has been characterized [2]. The aim of the study was to examine the possible role of bilitranslocase in the vasodilatation activity of flavonoids. As a source of flavonoids we used bilberries, which are abundant in anthocyanins that show strong affinity for bilitranslocase. Methods A bilberry extract, of which the anthocyanin content was quantified by HPLC-DAD analysis, was used. Anthocyanins were expressed as a standard of cyanidin 3-glucoside (mg/L). Thoracic aortic rings obtained from male Wistar rats were mounted in standard organ baths filled with Krebs-Henseleit solution, maintained at 37°C with a 95% O2 / 5% CO2 mixture. Rings were divided into four groups: control group (intact aortic rings), endothelium denuded rings, rings with nitric oxide synthase (NOS) activity inhibited by application of L-NNA (0.1 mmol/L) and rings with inhibited bilitranslocase-mediated membrane transport. In the last group, aortic rings were pre-incubated for 30 min with mono-specific polyclonal bilitranslocase antibodies (0.24 μg/mL). After inducing submaximal contraction (60 mmol/L KCl) in all studied groups, a chemically characterized bilberry extract was applied in increasing concentrations (0.5-20 mg/L). Vascular tone was measured isometrically by a mechano-electrical transducer. Further tests were done to check the expression of bilitranslocase in the vascular system (endothelial cell line EA.hy 926 and vascular smooth muscle cell line A7r5) by Western blot analysis using bilitranslocase antibodies. Results Western blot analysis showed the presence of bilitranslocase on both endothelial and smooth muscle cells. Bilberry extract relaxed aortic rings in a concentration-dependent manner in the control group, but neither in endothelium-denuded aortic rings nor in rings with inhibited NOS. The maximum relaxation (19.00 ± 2.01%, n = 5) observed at 20 mg/L in the group with inhibited bilitranslocase activity was significantly lower (p < 0.001) compared to the control group (34.95 ± 3.11%, n = 10). Conclusion Our results show that the vasodilatation activity of anthocyanins in bilberry extract is partly dependent on the bilitranslocase-mediated transport of flavonoids into the endothelium, followed by the activation of NOS. However, even though the bilitranslocase is also expressed on smooth muscle cells, its role in the vasodilatation activity on these cells remains negligible.

          Related collections

          Most cited references1

          • Record: found
          • Abstract: found
          • Article: not found

          Bioavailability of flavonoids: a review of their membrane transport and the function of bilitranslocase in animal and plant organisms.

          Fruits and vegetables are rich in flavonoids, and ample epidemiological data show that diets rich in fruits and vegetables confer protection against cardiovascular, neurodegenerative and inflammatory diseases, and cancer. However, flavonoid bioavailability is reportedly very low in mammals and the molecular mechanisms of their action are still poorly known. This review focuses on membrane transport of flavonoids, a critical determinant of their bioavailability. Cellular influx and efflux transporters are reviewed for their involvement in the absorption of flavonoids from the gastro-intestinal tract and their subsequent tissue distribution. A focus on the mammalian bilirubin transporter bilitranslocase (TCDB 2.A.65.1.1) provides further insight into flavonoid bioavailability and its relationship with plasma bilirubin (an endogenous antioxidant). The general function of bilitranslocase as a flavonoid membrane transporter is further demonstrated by the occurrence of a plant homologue in organs (petals, berries) where flavonoid biosynthesis is most active. Bilitranslocase appears associated with sub-cellular membrane compartments and operates as a flavonoid membrane transporter.
            Bookmark

            Author and article information

            Conference
            BMC Pharmacol
            BMC Pharmacology
            BioMed Central
            1471-2210
            2009
            12 November 2009
            : 9
            : Suppl 2
            : A56
            Affiliations
            [1 ]Institute of Pharmacology and Experimental Toxicology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
            [2 ]Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
            [3 ]Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
            Article
            1471-2210-9-S2-A56
            10.1186/1471-2210-9-S2-A56
            2778929
            4539f9eb-9daf-45a5-86a9-48ce9f4764b5
            Copyright ©2009 Žiberna et al; licensee BioMed Central Ltd.
            15th Scientific Symposium of the Austrian Pharmacological Society (APHAR) Joint meeting with the Hungarian Society of Experimental and Clinical Pharmacology (MFT) and the Slovenian Pharmacological Society (SDF)
            Graz, Austria
            19–21 November 2009
            History
            Categories
            Meeting Abstract

            Pharmacology & Pharmaceutical medicine
            Pharmacology & Pharmaceutical medicine

            Comments

            Comment on this article