Does B-HT 920 lower intraocular pressure in cats by interacting with alpha 2- and/or DA2 adrenoceptors?
Topical administration of B-HT 920 (50 micrograms) to the eyes of normal unanesthetized cats produced decreases in intraocular pressure and pupil diameter. The ocular hypotensive effect of B-HT 920 was eliminated by sympathectomy and pretreatment with sulpiride (2 mg/kg, s.c.). B-HT 920 also produced dose-related inhibition of contractions of the cat nictitans elicited by stimulating the pre- and postganglionic sympathetic trunks. B-HT 920-induced suppression of the contracting nictitans was antagonized more effectively by relatively selective DA2 antagonists, sulpiride and domperidone, than by rauwolscine, a relatively selective alpha 2-adrenoceptor antagonist. These data suggest that B-HT 920 produces ocular hypotension in the cat by interacting predominantly with DA2 receptor on peripheral sympathetic nerves.
Potter
D E
DE
Department of Pharmacology, Texas Tech University Health Sciences Center, Lubbock.
Burke
J A
JA
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D001767:Blinking / Q000187:drug effects; D002415:Cats; D005123:Eye / Q000294:innervation; D007429:Intraocular Pressure / Q000187:drug effects*; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011954:Receptors, Dopamine / Q000187:drug effects*; D017448:Receptors, Dopamine D2; D012025:Reflex, Pupillary / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D001381:Azepines; D011941:Receptors, Adrenergic; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; C024763:talipexole