Figure 1.

van't Hoff plots for ligand binding to A₁ adenosine receptors in rat brain membranes. (A) Binding experiments were conducted in 50 mM Tris-HCl pH 7.4 (A) with membranes not pretreated or pretreated with NEM. (B) Experiments were performed in 50 mM Tris-HCl pH 7.4, 2 mM triethanolamine, 1 mM EDTA, 5 mM MgCl₂, 100 mM NaCl, 1 mM dithiothreitol and 0.5% bovine serum albumin or, alternatively, in the same incubation medium containing in addition 10 μM GDP. K_D values for [³H]-DPCPX are from saturation experiments. K_H values for agonists, K_D and K_i values for antagonists are indicated by filled symbols, K_L values for agonists are shown as open symbols. The lines in the figure are the linear regression lines of lnK_A from 3–6 experiments for each compound versus (T⁻¹).