P2X7 receptors (P2X7R) are cation channels activated by extracellular ATP. They are expressed in cells of the haematopoetic lineage and play a key role in the normal inflammatory response. Enhanced P2X7R activation is implicated in chronic disease. P2X7R expression is up-regulated in models of renal injury and P2X7R deficiency/antagonism is renoprotective, attributed to reduced inflammation1. Despite this, P2X7R antagonists have not improved outcome for inflammatory diseases in clinical trial2. The receptor is also expressed in non-immune cells under normal conditions and this may be important in the disease process. Here, we used immunofluorescence to define P2X7R distribution in the kidney of male C57BL6/J mice. We used a commercially available polyclonal P2X7R antibody raised against a C-terminal sequence in exon 13 (APR-004, Alomone, Israel). Since the encoding gene, p2rx7, is highly polymorphic we first compared the antibody’s target sequence against known C57BL6/J mouse variants. The NCBI database (accessed 30 March 2015) identified 5 protein coding splice variants for P2X7R. P2X7-001 was the canonical full-length protein; the remaining forms exhibited variation in either the C terminal sequence or exon number. Antibody APR-004 recognised the full length variant, P2X7-001, and the variant P2X7-005, which has sequence variation in the N-terminus. In Western analysis of whole-kidney protein extracts, APR004 identified products of the predicted molecular weight (n=5). The expression profile of this antibody was then established using immunofluorescence. Male C57Bl6/J mice (n=3) were killed by cervical dislocation and the left kidney fixed by immersion fixation in 4% paraformaldehyde. Kidneys were then paraffin-embedded and sectioned at 6μm. Sections were blocked with 1% goat serum and incubated overnight with rabbit anti-P2X7 APR004 (1:1000). An HRP-conjugated secondary antibody was added, followed by a tyramide signal amplification step. APR004 consistently identified immune-positivity in the endothelium of the segmental, interlobular, interlobar and arcuate arteries. Punctate staining in the smooth muscle of arteries and arterioles was also observed and there was weak and diffuse intracellular staining in proximal tubules. These findings indicate that the canonical, full-length P2X7R variant is expressed in epithelial, endothelial and vascular cells of the kidney under normal, non-inflammatory conditions. The physiological function of P2X7R is not yet established but may be important if the full therapeutic potential of P2X7R antagonists is to be realised.