title: A second conponent of atropine mydriasis.
abstract: A patient with Waardenburg syndrome had, in addition to the classical findings, a semidilated fixed pupil which did not react to changes of illumination, to convergence, or to pilocarpine of phospholine iodide. However, it responded normally to locally applied drugs acting on the sympathetic system. The pupil dilated after application of atropine, homatropine, or cocaine. The effect of cocaine, but not of atropine and homatropine, was prevented by pretreatment with guanethidine. It is concluded that the mydriasis caused by atropine and homatropine is partly dependent upon a direct action on the radial smooth muscle.
mesh_terms: D001285:Atropine / Q000494:pharmacology*; D003042:Cocaine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006145:Guanethidine / Q000494:pharmacology; D006801:Humans; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects; D009184:Mydriatics / Q000494:pharmacology*; D011680:Pupil / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects; D014326:Tropanes / Q000494:pharmacology; D014849:Waardenburg Syndrome / Q000150:complications
chemical_list: D009184:Mydriatics; D014326:Tropanes; D001285:Atropine; D003042:Cocaine; D006145:Guanethidine