Figure 1.

The effect of bovine serum albumin (BSA) on BzATP-stimulated ethidium accumulation in cells expressing (A) human, (B) rat or (C) mouse P2X₇ receptors. Concentration-effect curves (CEC) to BzATP were obtained in the absence or presence of BSA. Data are the mean±s.e.mean of four experiments and are expressed as a percentage of the maximum response obtained in the absence of BSA. Lines through data points do not represent lines of best fit. Basal fluorescence values were not removed. In (A – C), CEC were obtained in sucrose buffer containing 0.5 mM CaCl₂ (sucrose) while in (C) CEC were also obtained in calcium-free sucrose buffer containing 0.1 mM EDTA (Sucrose EDTA). In (D), the ratios of EC₅₀ values determined in the presence of the indicated concentrations of BSA to those determined in the absence of BSA (Dose-ratio, DR) were calculated and are presented as a Schild plot. These data were obtained in either NaCl buffer (NaCl) or sucrose buffer containing either 0.5 mM CaCl₂ (sucrose) or 0.1 mM CaCl₂ (Sucrose 0.1 Ca).