Does NAD(P)H oxidase-derived H2O2 participate in hypotonicity-induced insulin release by activating VRAC in β-cells?
Autor: | Karim Louchami, Vadim Shlyonsky, Myrna Virreira, Renaud Beauwens, Willy Malaisse, Raphaël Crutzen, Emeline Hupkens, Abdullah Sener, Alain Boom |
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Rok vydání: | 2011 |
Předmět: |
medicine.medical_specialty
Patch-Clamp Techniques Physiology medicine.medical_treatment Clinical Biochemistry Pharmacology chemistry.chemical_compound Onium Compounds Insulin-Secreting Cells Physiology (medical) Internal medicine medicine Animals Insulin Voltage-Dependent Anion Channels Patch clamp Rats Wistar Betulinic Acid Cells Cultured Oxidase test NADPH Oxidases NOX4 Hydrogen Peroxide Plumbagin Anion channel activity Triterpenes Acetylcysteine Rats Glucose Endocrinology Hypotonic Solutions chemistry NAD(P)H oxidase Nitrobenzoates Models Animal Pentacyclic Triterpenes Reactive Oxygen Species Intracellular |
Zdroj: | Pflügers Archiv - European Journal of Physiology. 463:377-390 |
ISSN: | 1432-2013 0031-6768 |
Popis: | NAD(P)H oxidase (NOX)-derived H(2)O(2) was recently proposed to act, in several cells, as the signal mediating the activation of volume-regulated anion channels (VRAC) under a variety of physiological conditions. The present study aims at investigating whether a similar situation prevails in insulin-secreting BRIN-BD11 and rat β-cells. Exogenous H(2)O(2) (100 to 200 μM) at basal glucose concentration (1.1 to 2.8 mM) stimulated insulin secretion. The inhibitor of VRAC, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) inhibited the secretory response to exogenous H(2)O(2). In patch clamp experiments, exogenous H(2)O(2) was observed to stimulate NPPB-sensitive anion channel activity, which induced cell membrane depolarization. Exposure of the BRIN-BD11 cells to a hypotonic medium caused a detectable increase in intracellular level of reactive oxygen species (ROS) that was abolished by diphenyleneiodonium chloride (DPI), a universal NOX inhibitor. NOX inhibitors such as DPI and plumbagin nearly totally inhibited insulin release provoked by exposure of the BRIN-BD11 cells to a hypotonic medium. Preincubation with two other drugs also abolished hypotonicity-induced insulin release and reduced basal insulin output: 1) N-acetyl-L-cysteine (NAC), a glutathione precursor that serves as general antioxidant and 2) betulinic acid a compound that almost totally abolished NOX4 expression. As NPPB, each of these inhibitors (DPI, plumbagin, preincubation with NAC or betulinic acid) strongly reduced the volume regulatory decrease observed following a hypotonic shock, providing an independent proof that VRAC activation is mediated by H(2)O(2). Taken together, these data suggest that NOX-derived H(2)O(2) plays a key role in the insulin secretory response of BRIN-BD11 and native β-cells to extracellular hypotonicity. |
Databáze: | OpenAIRE |
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