Extracellular ATP Enhances mRNA Levels of Nitric Oxide Synthase and TNF-α in Lipopolysaccharide-Treated Raw 264.7 Murine Macrophages

Abstract

Extracellular ATP potentiates, by activation of P2y-type purinergic receptors, the production of NO induced by low doses of lipopolysaccharide (LPS) in the murine macrophagic cell line RAW 264.7 (Tonetti et al. (1994) Biochem. Biophys. Res. Commun. 203, 430-434). Release of TNF-α, known to be an autocrine factor for iNOS expression, was enhanced, too, following exposure of either LPS-induced or uninduced cells to externally added micromolar ATP. Reverse transcription-PCR experiments showed that extracellular ATP increases mRNA levels of both inducible NO synthase (iNOS) and of TNF-α to extents comparable to those of enzymatic and biological activities, respectively. These data demonstrate that activation of purinergic receptors by extracellular ATP results in an enhanced expression of the iNOS and TNF-α genes.