Immunohistochemistry of P2X7 receptors. Hind paw sections from control rats treated with saline (a) or oATP locally (c) or intravenously (e). After carrageenan induced inflammation, hind paws were submitted, to either saline (b), oATP local (d) or oATP intravenous (f) treatment. Notice the strong labelling on nerves and vessels in specimens treated only with saline, with variable presence of P2X7 which shows a general reduction after oATP local treatment, more evident after intravenous oATP treatment (original magnification 200x, P2X7 evidenced in brown, 3,3 diaminobenzidine, PGP 9.5 evidenced in blue, nithroblue tetrazolium). Data are representative of 5 experiments.