Dopamine activates the extracellular signal regulated kinase 1/2 (ERK 1/2) through a mechanism mediated by reactive oxygen species in proximal tubule cells

ACQUIER, A.; TOMÉ, J.; MORI SEQUEIROS GARCIA, M.; GOROSTIZAGA, A.; GOMEZ, N.; PAZ, C.; MENDEZ, C.F.

Buenos Aires

Simposio; International symposium-workshop: Renal regulation of blood pressure. Role of angiotensin and dopamine; 2012

American Physiological Society, Latinamerican initiative

Intrarenaly produced dopamine (DA) participates in the regulation of water and electrolyte homeostasis by regulating Na+,K+-ATPase activity through activation of D1- and D2-like receptors, stimulation of PKC and PLA2-mediated arachidonic acid (AA) release and generation of hydroxylated metabolites of AA. DA is metabolized mainly to 3,4-dihydroxyphenylacetic acid, a reaction that generates H2O2, but it can also be rapidly oxidized to DA semiquinone/quinone and can act as a source of reactive oxygen species (ROS). We thus aimed to study the participation of ROS in the signal transduction pathway triggered by DA in a proximal tubule-derived cell line of opossum origin (OK cells). DA promoted a fast and concentration dependent (10-12-10-6M) elevation of intracellular ROS, as detected by the fluorescent probe dichlorofluorescein diacetate. Pretreatment of the cells with the mitochondrial complex I inhibitor rotenone or by the selective PKC inhibitor Ro-318220 prevented DA-induced ROS elevation. DA promoted also a time-, and concentration-dependent stimulation of ERK1/2 phosphorylation and translocation, as detected by western blot and immunocytochemistry, that was abolished by the antioxidant N-acetylcysteine (NAC). DA stimulation of OK cells resulted also in a time-, and concentration-dependent increase of superoxide dismutase (SOD) and of transcription factor kB (NF-kB) activity, an effect that was blocked in the presence of NAC and of inhibitors of PKC and ERK1/2 activation. We conclude from our results that DA generates mitochondria-derived ROS that activate ERK1/2 and subsequently NF-kB and SOD activity at concentrations that exert a physiological regulation of renal function.