Figure 3. Dose-response effects of 5'-N-ethylcarboxamidoadenosine (NECA) on the monosynaptic reflex (MSR) (A) and the slow ventral root potential (VRP) (B) in the absence or presence of fixed concentrations (10 nM, 30 nM, and 100 nM) of antagonist, 8-cyclopentyltheophylline (CPT). Data are mean +/- SEM (n = 4-7). (C) Schild plots derived from the results shown in A and B. Data points are means of at least four experiments. The slopes of the regression lines are 1.045 +/- 0.066 for the MSR and 0.948 +/- 0.018 for the slow VRP. The intercept on the abscissa scale gives the pA²values of 8.26 and 8.37, equivalent to K^Dvalues of 5.5 nM for the MSR and 4.3 nM for the slow VRP, respectively.