Factors affecting solubilized dopamine-sensitive adenylate cyclase

Bovine striatal adenylate cyclase was solubilized with sodium cholate and assayed for its responsiveness to a variety of agents. Magnesium ions (0-20 mM), guanylyl-imidodiphosphate (10-50 microM), and striatal lipids were effective in increasing enzyme activity. The adenylate cyclase could be stimulated by dopamine, and neuroleptic drugs inhibited the effect of dopamine (50 microM) with potencies that paralleled their clinical potencies. The IC50 values for spiroperidol, haloperidol and chlorpromazine were 0.2, 3 and 500 nM respectively.