Human erythrocytes release ATP in a cyclic AMP-regulated manner

MONTALBETTI N, LAZAROWSKI E, SCHWARZBAUM PJ

Congreso; International Purine Meeting 2010; 2010

International Purine Meeting 2010

Human erythrocytes release ATP in response to various physiologically relevant stimuli, but the underlying mechanisms enablingATP release from red blood cells are not well defined. Exposure of human erythrocytes (4% hematocrit) to forskolin resulted inenhanced ATP release, which was dependent on the presence of the phosphodiesterase inhibitor papaverine (vehicle, 12 ±1 nM;100 microMpapaverine, 20±2 nM; 100 microMpapaverine and 30 microMforskolin, 42±3 nM) or 3-isobutyl-1-methylxanthine(IBMX) (vehicle, 13±2 nM; 30 microM IBMX, 22±3 nM; 30 microM IBMX and 30 microM forskolin, 49±5 nM). The betaadrenergicreceptor agonist isoproterenol dose-dependently (EC50 = 2.9±0.7 nM) promoted ATP release, and this release wascomparable in magnitude with that induced by forskolin. However, ATP release was dramatically potentiated (5- to 10-foldincrease) when isoproterenol and forskolin were combined. Since erythrocytes lack vesicles, we hypothesized that cyclic AMPstimulatedATP release reflects a conductivemechanism. Consistently with this hypothesis, ATP release from forskolin-stimulatederythrocytes was markedly reduced by preincubating the cells with 10 microM carbenoxolone, a non-selective hemichannelinhibitor. ATP release also was inhibited by the pannexin 1-selective blocking peptide (30 microM 10Panx1) but not by itsscramble control peptide. Our study suggests that agonists promoting cyclic AMP formation stimulate ATP release from humanerythrocytes via a pannexin 1-mediated pathway. 1- Supported by UBA, CONICET and ANPCyT (1432). 2- Supported by NIH.