Fig. 5.

Effect of buthionine sulfoximine (BSO) on the uptake of [³H]dopamine (DA) and [¹⁴C]choline (Chol) in PC12 cells. After an initial drug-free culture period of 48 hr, without a change of medium (see Materials and Methods), PC12 cells were kept in culture for an additional period of 24 hr in the absence (control) or presence of 10 μm BSO, respectively. Subsequently, the culture medium was removed and radioligand uptake was determined using a phosphate buffer to which both [³H]dopamine and [¹⁴C]choline had been added, as detailed in Materials and Methods. Data represent the mean ± SEM (n = 6) from two independent experiments and are expressed as percentage of control (i.e., uptake of either radioligand after 72 hr of culture in the absence of BSO). Under control conditions, the uptake of [³H]dopamine and [¹⁴C]choline amounted to 497,000 ± 10,900 and 11,600 ± 531 dpm (mean ± SEM), respectively. *p < 0.001 versus uptake of [³H]dopamine under control condition.