Receptor-mediated activation of the heterotrimeric G-protein Gs results in ATP release from erythrocytes.
BACKGROUND
Adenosine triphosphate (ATP), released from the erythrocyte in response to mechanical deformation, decreased oxygen tension or reduced pH, has been suggested to be an important determinant of vascular resistance in several vascular beds. Mechanical deformation-induced ATP release from rabbit and human erythrocytes was reported to require the activity of the cystic fibrosis transmembrane conductance regulator (CFTR), suggesting that a signal transduction pathway involving CFTR mediates ATP release from erythrocytes. Here we investigate the hypothesis that the heterotrimeric G-protein Gs is also involved in this signal transduction pathway.


METHODS
The heterotrimeric G-protein Gs was identified in rabbit and human erythrocyte membranes, using gel electrophoresis. The concentration of ATP released into a suspension of erythrocytes, incubated with iloprost or epinephrine, was measured using the luciferin/luciferase assay.


RESULTS
The 45 kDa form of the heterotrimeric G-protein Gs was identified 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 of Gs results in ATP release. These results are consistent with the hypothesis that Gs is a component of a signal transduction pathway for ATP release from erythrocytes.
Olearczyk
J J
JJ
Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, MA, USA. olearcjj@slu.edu
Stephenson
A H
AH
Lonigro
A J
AJ
Sprague
R S
RS
D000255:Adenosine Triphosphate / Q000097:blood*; D000818:Animals; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction
C505032:CFTR protein, human; D011943:Receptors, Adrenergic, beta; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate; D019205:GTP-Binding Protein alpha Subunits, Gs; D016285:Iloprost; D004837:Epinephrine