CENTRO DE INVESTIGACIONES CARDIOVASCULARES "DR. HORACIO EUGENIO CINGOLANI"
Unidad Ejecutora - UE
congresos y reuniones científicas
GPR30 activation is required for aldosterone-induced non-genomic stimulation of cardiac sodium/bicarbonate cotransporter
DE GIUSTI, VC; ORLOWSKI, A; CIANCIO, MC; GONANO, LA; VILA PETROFF, M; AIELLO, EA
Congreso; Gordon Researches Conferences: Cardiac Regulatory Mechanismis; 2014
Gordon Researches Conferences
The relevance of the rapid non-genomic effects of aldosterone (aldo) in the heart is increasingly appreciated. Through the activation of the classic mineralocorticoid receptor (MR), it has been demonstrated that aldo increases the reactive oxygen species (ROS) production and triggers the activation of the sodium/proton antiporter (NHE) in a non-genomic pathway. However, in the past year, it was proposed that the activation of the novel G protein-coupled receptor 30 (GPR30) mediates the non-genomic effects of aldo in vascular muscle. The aim of this study is to elucidate if the sodium/bicarbonate cotransporter (NBC) is stimulated by aldo, with particular emphasis upon if the activation of GPR30 could mediate this effect. NBC activity was evaluated in rat myocytes perfused with HCO3-/CO2 solution in the continuous presence of HOE 642 (NHE blocker) during recovery from acidosis (double NH4+ pulse, expressed as percentage of H+ flux (JH) at pHi 6.8 between the 2nd and the 1st pulse) using intracellular fluorescent measurements of BCECF-AM. Aldo enhanced NBC activity (), which was prevented by eplerenone (eple, MR antagonists), G15 (GPR30 blocker) but not by cicloheximide (ciclo, protein synthesis inhibitor), suggesting that the GPR30 participates in the non-genomic NBC stimulation induced by aldo. In concordance, G1 (GPR30 agonist) stimulated NBC, effect abrogated by G15 (). Aldo and G1-induced NBC stimulation was abolished by the ROS scavenger MPG () and apocinine (apo, NADPH oxidase inhibitor). Also, G15 prevented aldo and G1-induced ROS production, indicating that ROS participated as signaling molecules in this mechanism. The ERK kinase 1/2 is a crucial mediator in the MR-dependent non-genomic aldo signaling, so we investigated if ERK1/2 participates in aldo-induced NBC stimulation. The pre-incubation of the myocytes with U0126 (ERK1/2 blocker) did not change NBC stimulation induced by aldo. Interestingly, aldo increased the phosphorylation level of the kinase, which was prevented by eple but not by G15 (). Moreover, G1 did not increase ERK1/2 phosphorylation, supporting the idea that aldo-induced NBC stimulation though GPR30 activation is independent of ERK1/2 pathway. Finally, certain studies have suggested that eple might have nonspecific effects. Our results showed that eple prevented G1-induced NBC activation () and also that eple alone induced NBC stimulation, which was abolished by G15 (), indicating that could be acting as a partial agonist of GPR30. In conclusion, our results suggest that the GPR30 could be a novel target, which could open significant opportunities in the development of new pharmacological strategies for cardiovascular diseases. Also, the results call the attention about the real effects of MR antagonists and open new investigations upon how they have so beneficial results in the clinical practice.