Effects of pimozide on the response of smooth muscle to non-dopamine agonists and calcium.
Pimozide inhibits acetylcholine and histamine-induced contractions of the isolated guinea-pig ileum and noradrenaline-induced contractions of the isolated rat vas deferens in a non-competitive manner. In order to explore the nature of this inhibitory effect, we investigated pimozide's effects on calcium-induced contractions of deplorized guinea-pig ileum. In this case the antagonism elicited was competitive. Therefore caution is indicated in the use of pimozide to provide indirect proof of the existence of peripheral dopamine receptors.
D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006168:Guinea Pigs; D006633:Histamine Antagonists; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000037:antagonists & inhibitors; D010868:Pimozide / Q000494:pharmacology*; D051381:Rats; D014649:Vas Deferens / Q000187:drug effects
D006633:Histamine Antagonists; D010868:Pimozide; D000109:Acetylcholine; D002118:Calcium; D009638:Norepinephrine