Ocular inhibitory effects of the dopamine DA2 agonist (Ha-118) in cats and rabbits.

Abstract

1. Topical administration of the dopamine (DA2) receptor agonist, Ha-118, produced unilateral ocular hypotension and miosis in normal cats. 2. The ocular hypotensive and mitotic effects of Ha-118 were not observed in surgically sympathectomized cats indicating that an intact sympathetic pathway is necessary to demonstrate activity. 3. Ha-118 caused dose-dependent suppression of contractions of the cat nictitating membrane (CNM) elicited by electrical stimulation of the pre- and postganglionic sympathetic nerve trunks but not by exogenously administered noradrenaline suggesting that Ha-118 affected prejunctional but not ganglionic or postjunctional receptors. 4. Sulpiride antagonized Ha-118-induced inhibition of neuronally mediated contractions in the CNM suggesting an interaction at DA2 receptors. 5. Topical administration of Ha-118 inhibited the rise in intraocular pressure induced by oral water loading in rabbits. 6. Topical pretreatment with metoclopramide, a DA2 antagonist, inhibited the ocular antihypertensive effect of Ha-118 in rabbits. 7. These studies demonstrate that Ha-118 decreased intraocular pressure (IOP) and pupil diameter (PD) in the cat and that this activity can be correlated with suppression of peripheral sympathetic tone in the CNM.

• Authors: D E Potter, J A Burke, M J Ogidigben
• Journal: Journal of autonomic pharmacology (J Auton Pharmacol) Vol. 10 Issue 3 Pg. 153-61 (Jun 1990) ISSN: 0144-1795 [Print] England
• PMID: 1974256 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Dopamine Agents
• Quinolines
• Water
• Ha 118
• Metoclopramide
• Norepinephrine

Topics

• Animals
• Cats
• Dopamine Agents (antagonists & inhibitors, pharmacology)
• Electric Stimulation
• Female
• In Vitro Techniques
• Intraocular Pressure (drug effects)
• Male
• Metoclopramide (pharmacology)
• Molecular Structure
• Nictitating Membrane (drug effects)
• Norepinephrine (pharmacology)
• Pupil (drug effects)
• Quinolines (antagonists & inhibitors, pharmacology)
• Rabbits
• Water