Fig. 3.
Effect of antagonists on basal [35S]GTPγS binding to membranes from CHO cells expressing MOPr. a Concentration-response curve for GSK1521498 (black square), naloxone (black circle), naltrexone (white circle), 6-β-naltrexol (black up-pointing triangle) and nalmefene (white square) in CHO cell membranes overexpressing MOPr. Mean data are expressed as percentage of the basal binding, determined in the absence of ligands. At concentrations greater than 0.4 nM, GSK1521498 produced a significant inhibition of basal [35S]GTPγS binding (p < 0.001, ANOVA on log-transformed raw data, with treatment and plates as independent factors). b Drugs were tested at a final concentration of 1 μM on membranes prepared from CHO cells expressing a low level of MOPr. Values are expressed as a percentage of the basal value in the absence of drug, which was taken as 100 % in each experiment. Values shown as means ± SEM from five separate experiments in each case. None of the drugs had a significant effect on basal [35S]GTPγS binding (one sample t test)