P2X(1) RECEPTOR ACTIVATION IN HL-60 CELLS

Recent cloning of the human P2X(1) receptor revealed high levels of it s messenger RNA in differentiated promyelocytes (HL60 cells), We found expression of P2X(1) receptor protein in HL60 cells by radioligand bi nding, by immunohistochemistry, using a receptor specific antibody, an d by electrophysiology, The currents elicited by adenosine triphosphat e (ATP) had the expected properties of P2X(1) receptors (rapid desensi tization, mimicked by alpha,beta-methylene-ATP). However, these curren ts were only observed in cells that were pretreated with apyrase, whic h destroys extracellular ATP, or with suramin, a P2X receptor antagoni st, This implies that HL60 cells release ATP, which chronically desens itizes the receptor, ATP release was detected by direct measurement, u sing the luciferin-luciferase assay. It is concluded that functional P 2X(1) receptors are present in the membrane of differentiated HL60 cel ls. (C) 1996 by The American Society of Hematology.