TABLE 1

Analysis of biphasic concentration-response profiles for the actions of PNU-69176E on [³H]5-HT binding (Fig. 2) and GTPγ [³⁵S] binding (Fig. 4) to the human 5-HT_2C receptor in HEK293 cell membranes using a two-site logistic equation

Effects of PNU-69176E at various concentrations on [³H]5-HT (2 nM) binding to the 5-HT_2C receptor were measured in HEK293 cell membranes expressing the receptor using filtration techniques. Their effects on GTPγ [³⁵S] binding were measured in the same membrane preparation and as a function of drug concentrations with or without mesulergine in excess (100 μM), and they were normalized to the level observed with 5-HT at a saturating concentration (10 μM). Mesulergine by itself showed no appreciable effects on GTPγ [³⁵S] binding, but it blocked PNU-69176E-induced GTPγ [³⁵S] binding.