Adrenaline stimulates H2O2 generation in liver via NADPH oxidase |
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Authors: | Antonio Díaz-Cruz Raquel Guinzberg Ruy Guerra Magdalena Vilchis Daniel Carrasco Francisco J García-vázquez |
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Institution: | 1. Department of Animal Nutrition and Biochemistry, Faculty of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico (UNAM), Mexico City, Mexicoadc@servidor.unam.mx;3. Department of Biochemistry, Faculty of Medicine, UNAM, P.O. Box 70159, Mexico City, Mexico;4. Department of Animal Nutrition and Biochemistry, Faculty of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico (UNAM), Mexico City, Mexico;5. Laboratory of Molecular Pathology, National Institute of Pediatrics (INP), Ministry of Health, Mexico City, Mexico |
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Abstract: | It is known that adrenaline promotes hydroxyl radical generation in isolated rat hepatocytes. The aim of this work was to investigate a potential role of NADPH oxidase (Nox) isoforms for an oxidative stress signal in response to adrenaline in hepatocytes. Enriched plasma membranes from isolated rat liver cells were prepared for this purpose. These membranes showed catalytic activity of Nox isoforms, probably Nox 2 based on its complete inhibition with specific antibodies. NADPH was oxidized to convert O2 into superoxide radical, later transformed into H2O2. This enzymatic activity requires previous activation with either 3 mM Mn2+ or guanosine 5′-0-(3-thiotriphosphate) (GTPγS) plus adrenaline. Experimental conditions for activation and catalytic steps were set up: ATP was not required; S0.5 for NADPH was 44 μM; S0.5 for FAD was 8 μM; NADH up to 1 mM was not substrate, and diphenyleneiodonium was inhibitory. Activation with GTPγS plus adrenaline was dose- and Ca2+-dependent and proceeded through α1-adrenergic receptors (AR), whereas β-AR stimulation resulted in inhibition of Nox activity. These results lead us to propose H2O2 as additional transduction signal for adrenaline response in hepatic cells. |
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Keywords: | Adrenergic receptors adrenaline hydrogen peroxide liver cell membranes NADPH oxidase (Nox) ROS signaling |
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