Fig. 7.

Inhibition of [³H]DHR binding by MPP⁺ is competitive. [³H]DHR saturation studies were performed in the presence of 0, 1, and 5 mmMPP⁺. The double-reciprocal plot demonstrates that increasing concentrations of MPP⁺ decreases the apparent affinity of [³H]DHR binding without changing the number of binding sites.