Figure 4.

Effect of 24 h treatment with norepinephrine on binding of [³H]rauwolscine. Cell were incubated with 0.3 μM norepinephrine or vehicle for 24 h and membranes prepared. Specific binding to the alpha-2C adrenergic receptor was determined using 0.40 nM [³H]rauwolscine. The values are mean ± SEM for 7 experiments using two different clones. Each experiment consisted of three culture dishes with norepinephrine and three without norepinephrine for each clone and each dish was assayed in duplicate. The amount of specific binding in the wild-type following the norepinephrine pretreatment was significantly different from the binding in the control by a t-test (p < 0.05). The binding levels of the two mutant clones were not different following norepinephrine pretreatment as compared to control.