ESPELT Maria Victoria
congresos y reuniones científicas
Comparative analysis of P receptor-mediated induction of regulatory volume decrease in cells from teleosts and mammals
ALVAREZ C.L.; ESPELT MV; PAFUNDO DE; KRUMSCHNABEL G; SCHWARZBAUM PJ
Congreso; 26th Congress of the European Society for Comparative Physiology and Biochemistry; 2009
European Society for Comparative Physiology and Biochemistry
In most cells hypotonic exposure causes cell swelling followed by ATPrelease. The accumulated extracellularATP (ATPe)mayact on P2 receptorsto activate a recovery of cell volumeknownas volume regulatory decrease(RVD).We have studied the RVD of goldfish hepatocytes, as compared totrout hepatocytes and a human hepatoma cell line (HEPG2).In hypotonic medium the three cell types undergo swellingfollowed by a non-linear accumulation of ATPe. Cells increased theirvolume about 1.6 times, with subsequent 60% RVD after 40 min (troutand HEPG2 cells) or no RVD (goldfish). Addition of apyrase (anucleotide remover) or P2 blockers led to a significant inhibition ofRVD in trout cells, but had no effect in HEPG2. In goldfish hepatocytesextracellular ATPγS (a non-hydrolyzable ATP analogue) induced RVDin a concentration-dependent manner (150 μM, K0.5=570 nM), aresponse which was abolished by antagonists of P2 receptors. Sincegoldfish hepatocytes do release ATP, we decreased the assay mediumseveral fold to verify if endogenous extracellular ATP could accumulatein sufficient concentrations to trigger RVD. Accordingly, with a 1:40 v/vdilution of cells (height of the medium108μm), goldfish cells had a 56%RVD that could be abolished 73% by P2 antagonists.Thus, as a preliminary conclusion, although an RVD could beobserved in goldfish, trout and HEPG2 cells, the activation patternsare different. RVD can be triggered under standard hypotonicconditions (trout and HEPG2), or when the extracellular medium issufficiently low to accumulate ATPe (goldfish). Up to now, the RVD ofHEPG2 cells does not seem to require activation by ATPe.