50 mg/day for two days, thereafter a flexible dosage schedule was followed until therapeutic effect achieved.

One hundred microlitres of [3H]SCH23390 (1 nM, 90 Ci/mmol), competing drug solution (100 mkl of variable concentrations) and 50 mM Tris-HCl buffer (700 gl) containing no NaCl or KCI were placed in glass tubes. The solutions were stirred using a vortex mixer. One hundred microlitres of membrane preparation (2.5 mg wet tissue/tube) were added and the solution was again stirred using a vortex mixer. Solutions were incubated for 30 min at 37 C. Incubations were terminated by rapid filtration under vacuum using Whatman GF/B filters (24 mm diameter). The tubes and filters were rinsed with 6 ml ice-cold saline. The filters were punched out and placed in a 20 ml glass vial with 10 ml scintillation cocktail. After the samples stood six hours, radioactivities were measured using a Beckman LS 7800 liquid scintillation counter. The specific bound was defined as the total amount of [3H]SCH23390 bound (zero unlabelled ligands) minus the nonspecific amount bound (binding in presence of 1mkM SCH23390).