Figure 3.

α-PHP is an antagonist/inverse agonist of M₂R-β-arrestin recruitment with nanomolar potency. (A) Oxotremorine dose-dependently stimulated β-arrestin recruitment. (B) α-PHP blocked effects of oxotremorine (EC₈₀ concentration) at M₂Rs and, moreover, decreased β-arrestin recruitment below basal* levels, suggesting inverse agonist activity. Data are shown as normalized means (±SEM) of two, independent determinations, with oxotremorine tested at each concentration in duplicate and α-PHP tested in quadruplicate. [*Basal signaling is defined as the normalized RLUs emitted by untreated cells.]