Shuttle-box avoidance behavior of mice treated with nifedipine in combination with nicotine or physostigmine.

Nicotine and physostigmine, given alone, slightly improved shuttle-box avoidance acquisition in mice. the dihydropyridine calcium channel inhibitor nifedipine, ineffective alone, enhanced the avoidance facilitating action of nicotine, but prevented the slight improving action of physostigmine. The results confirm that calcium channel blockers can interfere with the effects of centrally acting drugs and may augment the facilitation of learning induced by some of them. However, a comparison of the effects of nifedipine with those of the noncalcium antagonist vasodilator hydralazine suggests that hypotensive action of calcium channel blockers may interfere with the behavioral action related to specific neuronal changes due to calcium channel blockade. This may be particularly important in cases in which hypotensive action is exerted by the agent used in combination with the calcium channel blocker.