BACKGROUND: Adenosine triphosphate (ATP), released from the erythrocytein response to mechanical deformation, decreased oxygen tension or reduced pH, has been suggested tobe an important determinant of vascular resistance in several vascular beds. Mechanical deformation-inducedATP release from rabbit and human erythrocytes was reported to require the activity of the cystic fibrosistransmembrane conductance regulator (CFTR), suggesting that a signal transduction pathway involving CFTRmediates ATP release from erythrocytes. Here we investigate the hypothesis that the heterotrimeric G-proteinGs is also involved in this signal transduction pathway.
Materials and methods: The heterotrimeric G-proteinGs was identified in rabbit and human erythrocyte membranes, using gel electrophoresis. The concentrationof ATP released into a suspension of erythrocytes, incubated with iloprost or epinephrine, was measuredusing the luciferin/luciferase assay.
RESULTS: The 45 kDa form of the heterotrimeric G-protein Gs wasidentified in rabbit and human erythrocyte membranes. Incubation of rabbit erythrocytes with iloprost(n=18) or epinephrine (n=6) increased the ATP concentration by 106+/-16% and 156+/-54%, respectively.Epinephrine-induced changes in ATP concentrations were prevented by pretreatment with propranolol.
CONCLUSIONS:The heterotrimeric G-protein Gs is present in erythrocyte membranes. Receptor-mediated activation ofGs results in ATP release. These results are consistent with the hypothesis that Gs is a component ofa signal transduction pathway for ATP release from erythrocytes.

Keywords: ATP, erythrocyte, heterotrimeric G-protein Gs