Effects of calcium antagonists on phencyclidine behaviors.

The calcium antagonists nifedipine and verapamil were evaluated for their potential behavioral interactions with phencyclidine induced changes in mouse rotarod performance and motor activity. Nifedipine (2 and 10 mg/kg) and verapamil (2 mg/kg) significantly potentiated impairment of rotarod performance produced by phencyclidine. These doses of nifedipine and verapamil did not by themselves affect rotarod performance. This action does not appear to be dependent on the hypotensive properties of these drugs, since hypotensive doses of prazosin did not alter the effect of phencyclidine on rotarod performance. Nifedipine, 4.0 mg/kg, antagonized increases in ambulatory motor activity, and potentiated decreases in vertical motor activity (rearing) induced by phencyclidine. The effects of calcium antagonists to alter the behavioral actions of phencyclidine in mice may occur through an interaction with the dihydropyridine calcium antagonist binding site present in the central nervous system.