CALCIUM AGONISTS AND ANTAGONISTS OF THE DIHYDROPYRIDINE TYPE - EFFECTON NICOTINE-INDUCED ANTINOCICEPTION AND HYPOMOTILITY

The influence of a calcium agonist (BAYK 8644) and several calcium cha nnel blockers on nicotine-induced antinociception was investigated in mice. The effect of nicotine was sharply increased by BAYK 8644. This potentitation by BAYK 8644 was blocked by pretreating the animals with nifedipine at 2 and 10 mg/kg. The calcium channel antagonigts, nifedi pine and nimodipine at doses that had no effect on tail-flick time, re duced significantly the antinociception induced by nicotine (1.5 mg/kg , s.c.). However, the effect of verapamil on nicotine was not signific ant. These results indicate that DHP calcium channels (type L-channel) play a role in some of the pharmacological effects of nicotine, parti cularly, locomotor activity and antinociception.