ENDOTHELIN EFFECTS ON INTRACELLULAR CALCIUM DYNAMICS IN SON OF THE RAT.

G. PERFUME; J. FILOSA; L. BIANCIOTTI; J. STERN; M. VATTA

Mar del Plata, Buenos Aires

Congreso; LIII REUNION CIENTIFICA ANUAL, Sociedad Argentina de Investigación Clínica; 2008

SAIC

ENDOTHELIN EFFECTS ON INTRACELLULAR CALCIUM DYNAMICS IN SON OF THE RAT. G. Perfume1, J. Filosa2, L. Bianciotti1, J. Stern2, M. Vatta1. 1Catedras de Fisiología (IQUIMEFA-CONICET) y Fisiopatología, Facultad de Farmacia y Bioquímica-UBA; 2Department of Physiology. Medical Collage of Georgia. Endothelins has been shown to activate Ca2+ dependent mechanisms. ET-1 and ET-3 increased intracellular Ca2+ concentration due to the activation of voltage dependent Ca2+ channels and the release from intracellular stores as it was demonstrated in previous works. A deficit in TH activity induced by both peptides involved Ca2+ dependent mechanism that included extracellular and intracellular Ca2+ and NO/cGMP/PKG pathway. Since SON, known to be a sympatoinhibitory nucleus of the anterior hypothalamus, modulate cardiovascular functions, desbalance in both neurotransmitters and neuropeptides are associated with alterations in peripheral blood pressure. However, the precise Ca2+ mechanism mediating ETs actions within the SON are not completely understood. Using real time calcium imaging confocal microscopy, we addressed here the complex endothelin modulation of intracellular calcium dynamics in SON, including the relevant role of the glia in the endothelins response. We aimed here the participations of NO in ETs effects by determination of NO with DAF indicator. Results showed that 100 nM ET-1 increased intracellular Ca2+ concentration in both neurons and glial cells with two different behaviors. Neurons (N) and astrocytes (A) increased Ca2+ concentration at the same time showing the same peak time (N:116.0±6,5vs A:124.7±7.2*) and same amplitude (N:1.9±0.1 vs A:1.9±0.2*) in the first cells population observed. The second one showed that astrocytes responded to ET-1 later than neurons (N:158.5±30.2 vs A:196.8±15.6*) but the amplitude was higher (N:2.4±0.1 vs A:2.9±0,2*). It was observed that in presence of 100 nM thapsygargine, ETs response was abolished in the two populations of cells. Moreover, experiments were carried out in Ca2+ free medium and the increased of intracellular Ca2+ a concentration induced by ETs was still observed(N: 222.1±67. 2vs A: 225.3±20.1 *), (N: 2.1±0.1 vs A: 2.1±0.4*). NO production and the amount of producer cells were significantly increased in both neuronal (DAF: 100.0±7.9 vs ET: 172.4±5.9 *), and non neuronal cells (DAF: 100.0±15.0 vs ET: 154.2±16.1*). Taken these findings together, we conclude that in the SON ETs mediate their biological effects trough Ca2+ mechanism and NO production in both neurons and non neuronal cells, showing two types of cells populations. Furthermore, ETs effects on Ca2+ concentration were due to release from intracellular stores and not from extracellular Ca2+ in both cases.