Effects of some ergot alkaloids on dopamine receptors of molluscan smooth muscle.
Some ergot alkaloids relaxed catch contraction of an isolated molluscan smooth muscle (anterior byssus retractor muscle of Mytilus edulis). Haloperidol, a competitive dopamine antagonist, shifted the dose response curves of ergot alkaloids, but methysergide did not. Bromocriptine, a potent dopaminergic ergot alkaloid, did not relax catch contraction. These results suggest that relaxation of catch contraction by some ergot alkaloids is mediated through dopamine receptors of this muscle, but dopamine receptors of this muscle seem to be somewhat different from those of mammalian brain.
D000818:Animals; D049872:Bivalvia / Q000187:drug effects*; D004347:Drug Interactions; D004876:Ergot Alkaloids / Q000494:pharmacology*; D006220:Haloperidol / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011954:Receptors, Dopamine / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology
D004876:Ergot Alkaloids; D011954:Receptors, Dopamine; D012701:Serotonin; D006220:Haloperidol