Pharmacological characterization of P2X7 receptors in rat peritoneal cells

Objective and design: P2X(7) receptor activation by ATP results in the release of IL-1 beta and IL-18. Prolonged stimulation can lead to pore formation and cell death. In this study we pharmacologically characterized P2X(7) receptors on rat peritoneal cells (RPC) and on 1321N1 cells transfected with rat P2X(7) receptor (1321rP2X(7)-11). Materials and methods: RPC were isolated from rats by lavage. P2X(7) agonist induced pore formation in RPC was measured by EtBr uptake. P2X(7)-stimulated pore formation and Ca++ influx in 1321rP2X(7)-11 cells were measured by a fluorometric imaging plate reader. The effects of pyridoxal phosphate-6-azo phenyl -2'-4'-disulfonic acid (PPADS) on pore formation and Ca++ influx were examined in both RPC and 1321rP2X(7)-11.P2X(7)-mediated IL-1 beta release in RPC and the effect of PPADS were determined. Results: RPC express functional P2X(7) receptors that were activated by ATP analogs with a rank order of potency of 2'-3'-O-(4-Benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) > ATP > alpha, beta-methylene ATR Activation of P2X(7) receptors by BzATP was inhibited by PPADS. Similar results were also obtained in 1321rP2X(7)-11 cells. Activation of P2X(7) receptors on RPC resulted in IL-1 beta secretion, which was inhibited by PPADS. Conclusions: R-PC express functional P2X(7) receptors that form pores and mediate the release of IL-1 beta.