Effects of nomifensine on the isolated vas deferens of the rat.
The effects of nomifensine on the rat isolated vas deferens was studied. Nomifensine (7.60 X 10(-11) molar--7.60 X 10(-8) molar) enhanced the stimulant effects of dopamine and prevented the inhibitory action of pimozide on dopamine-induced contractions. Higher concentrations of nomifensine blocked the effects of dopamine noncompetitively (pD2' = 7.25 +/- 0.12). Nomifensine (7.60 X 10(-9) molar--3.80 X 10(-6) molar) enhanced noradrenaline-induced contractions and reduced phentolamine-induced antagonism of noradrenaline. Higher concentrations of nomifensine blocked the effects of noradrenaline competitively (pA2 = 5.50 +/- 0.06). Guanethidine induced supersensitivity of the vas to noradrenaline and further enhanced the potentiating effect of nomifensine. The effect of 5-HT was reduced competitively by nomifensine (pA2 = 7.50 +/- 0.10). Desipramine produced a similar preferential enhancement of dopamine-induced contractions and antagonized dopamine at higher concentrations. It is concluded that nomifensine may act prejunctionally by inhibiting uptake of the amines and postjunctionally by blocking the receptors.
D000818:Animals; D003891:Desipramine / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology; D004347:Drug Interactions; D006145:Guanethidine / Q000494:pharmacology; D066298:In Vitro Techniques; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009627:Nomifensine / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010868:Pimozide / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects
D007546:Isoquinolines; D010868:Pimozide; D009627:Nomifensine; D012701:Serotonin; D003891:Desipramine; D004298:Dopamine; D009638:Norepinephrine; D010646:Phentolamine; D006145:Guanethidine