Human erythrocytes release ATP in a cyclic AMP-regulated manner

1. N. MONTALBETTI, LAZAROWSKI E, SCHWARZBAUM P.

Tarragona, España.

Conferencia; Purines 2010: Adenine nucleosides and nucleotides in biomedicine.; 2010

Human erythrocytes release ATP in response to various physiologically relevant stimuli, but the underlying mechanisms enabling ATP release from red blood cells are not well defined. Exposure of human erythrocytes (4% hematocrit) to forskolin resulted in enhanced ATP release, which was dependent on the presence of the phosphodiesterase inhibitor papaverine (vehicle, 12 ±1 nM; 100 microM papaverine, 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 betaadrenergic receptor agonist isoproterenol dose-dependently (EC50 = 2.9±0.7 nM) promoted ATP release, and this release was comparable in magnitude with that induced by forskolin. However, ATP release was dramatically potentiated (5- to 10-fold increase) when isoproterenol and forskolin were combined. Since erythrocytes lack vesicles, we hypothesized that cyclic AMPstimulated ATP release reflects a conductivemechanism. Consistently with this hypothesis, ATP release from forskolin-stimulated erythrocytes was markedly reduced by preincubating the cells with 10 microM carbenoxolone, a non-selective hemichannel inhibitor. ATP release also was inhibited by the pannexin 1-selective blocking peptide (30 microM 10Panx1) but not by its scramble control peptide. Our study suggests that agonists promoting cyclic AMP formation stimulate ATP release from human erythrocytes via a pannexin 1-mediated pathway. 1- Supported by UBA, CONICET and ANPCyT (1432). 2- Supported by NIH.