Images captured on phosphor screens were visualized using a Cyclone Storage Phosphor Scanner (Packard Bioscience) and data were analyzed using the OptiQuant program associated with scanner. Images were quantified by densitometric analysis with [14C] standards. A brain paste standard assay was performed to determine the correction factor necessary to calculate nCi/g for [35S] from nCi/g for [14C], as previously described (Sim and Childers, 1997). Net agonist-stimulated [35S]GTPγS binding was calculated by subtracting basal binding (obtained in the absence of agonist) from agonist-stimulated binding. Data were reported as mean values ± S.E.M.
