RESUMEN
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 O(2) into superoxide radical, later transformed into H(2)O(2). This enzymatic activity requires previous activation with either 3 mM Mn(2+) or guanosine 5'-0-(3-thiotriphosphate) (GTPgammaS) plus adrenaline. Experimental conditions for activation and catalytic steps were set up: ATP was not required; S(0.5) for NADPH was 44 microM; S(0.5) for FAD was 8 microM; NADH up to 1 mM was not substrate, and diphenyleneiodonium was inhibitory. Activation with GTPgammaS plus adrenaline was dose- and Ca(2+)-dependent and proceeded through alpha(1)-adrenergic receptors (AR), whereas beta-AR stimulation resulted in inhibition of Nox activity. These results lead us to propose H(2)O(2) as additional transduction signal for adrenaline response in hepatic cells.
Asunto(s)
Agonistas Adrenérgicos/farmacología , Activación Enzimática/efectos de los fármacos , Epinefrina/farmacología , Hepatocitos/enzimología , Peróxido de Hidrógeno/metabolismo , Extractos Hepáticos/metabolismo , NADPH Oxidasas/metabolismo , Oxidantes/metabolismo , Animales , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Hepatocitos/citología , Hepatocitos/efectos de los fármacos , Masculino , Ratas , Ratas Wistar , Receptores Adrenérgicos/química , Receptores Adrenérgicos/metabolismoAsunto(s)
Citosol/metabolismo , Extractos Hepáticos/metabolismo , Microsomas/metabolismo , Naftoquinonas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Animales , Antineoplásicos/uso terapéutico , Citosol/enzimología , Espectroscopía de Resonancia por Spin del Electrón , Humanos , Microsomas/enzimología , Estructura Molecular , NADP/metabolismo , NADPH-Ferrihemoproteína Reductasa/metabolismo , Naftoquinonas/química , Naftoquinonas/farmacología , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Oxidación-Reducción , Especies Reactivas de Oxígeno/toxicidadRESUMEN
By means of starch gel electrophoresis and specific staining, molecular forms of aspartate aminotransferase and soluble esterases have been investigated in liver extracts of individuals from a population of Zenaida auriculata. Four alleles at the locus corresponding to soluble or cytoplasmic aspartate aminotransferase have been demonstrated. Distribution of phenotypes in the population is in perfect agreement with that expected according to the Hardy - Weinberg law. A large incidence of variants of two fractions of esterases has been found. This variability is, with all probability, genetically determined. The importance of this type of studies to assess genetic structure and dynamics of animal population is emphasized.