Endothelial nitric oxide synthase (eNOS) and P2X4 receptor (P2X4R) coimmunoprecipitated in cardiac ventricular myocytes of wild-type (WT) and P2X4-Tg hearts. A, WT myocyte lysates were incubated overnight with anti-eNOS antibody or with nonspecific IgG as control. The isolated complex was subjected to Western blot (WB) analysis and probed with eNOS (top) and P2X4 (bottom) antibodies. IP indicates immunoprecipitation; and Tg, transgenic. As a control, eNOS coimmunoprecipitated itself. Coimmunoprecipitation of P2X4R with eNOS antibody (lane 3) but not with control IgG (lane 2) is shown. B, Same experiment as in A conducted in P2X4-Tg myocytes. C, Immunostaining of eNOS (green), P2X4R (red), and merged image is shown for a P2X4R-overexpressing Tg cardiac myocyte.