Enhancement by nifedipine of cholinergic-induced depression of locomotor activity in mice.

The dihydropyridine calcium channel blocker nifedipine did not affect spontaneous locomotor activity in mice when given alone but enhanced the depressant effects of the muscarinic receptor agonist oxotremorine and of the acetylcholinesterase inhibitor physostigmine. Such a behavioral depression might be due to neuronal changes induced by central calcium channel blockade combined with cholinergic activation. However, an involvement of hemodynamic factors, related to peripheral vasodilatation, cannot be excluded as locomotor depressant effects were also exerted by combinations of the two cholinomimetic agents with hydralazine, a non-calcium antagonist vasodilator.