Citation: Iravani , M M & Zar , M A 1993 , ' Differential-effects of Nifedipine on nerve-mediated and noradrenaline-evoked contractions of rat anococcygeus muscle ' European Journal of Pharmacology , vol 250 , no. 1 , pp. 193-195 . DOI: 10.1016/0014-2999(93)90643-V
In rat anococcygeus muscle the inhibitory effect of nifedipine (0.01. 0.1, 1.0 and 10 muM) was determined on adrenergic twitches in response to electrical field stimulation (trains of 4 pulses, 0.1 ms pulse duration. 10 Hz) and on twitch-matching contractions evoked by noradrenaline. Nifedipine concentration-dependently reduced the neurogenic twitch with an IC50 of 0.083 muM. Nifedipine reduced the noradrenaline-evoked contraction to a markedly lesser degree (IC50 > 10 muM). The difference in the magnitude of inhibition of electrically evoked twitch and twitch-matching noradrenaline-evoked contraction was statistically significant at every concentration of nifedipine. It is concluded that inhibition of the twitch by nifedipine involves some other mechanism(s) in addition to its Ca2+ Channel blocking property in smooth muscle.