Abstract |
1. Experiments were undertaken to determine if the imidazoline/alpha2- adrenoceptor agonist, rilmenidine, would produce mydriasis in cats and, if so, to delineate its site of action and determine if this effect is mediated by imidazoline receptors or alpha2-adrenoceptors. 2. Rilmenidine produced dose-related pupillary dilator responses in pentobarbital anaesthetized cats that were independent of sympathetic innervation to the iris but were dependent upon intact parasympathetic neuronal tone. The ED50 for rilmenidine-induced pupillary dilation was approximately 200 microg kg(-1), i.v., and was sustained for at least 1 h. 3. The highly selective alpha2-adrenoceptor antagonist, RS-79948, administered either before or after rilmenidine, antagonized rilmenidine-induced mydriasis. Neuronally induced reflex inhibition of parasympathetic nerve activity was also inhibited by administration of RS-79948. 4. These results suggest that rilmenidine acts like clonidine to produce pupillary dilation by inhibition of parasympathetic tone to the iris sphincter and that this central nervous system parasympatho-inhibition is mediated by alpha2-adrenoceptors, rather than imidazoline receptors.
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Authors | M C Koss |
Journal | Autonomic & autacoid pharmacology
(Auton Autacoid Pharmacol)
Vol. 23
Issue 1
Pg. 51-6
(Feb 2003)
ISSN: 1474-8665 [Print] England |
PMID | 14565538
(Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Adrenergic alpha-2 Receptor Agonists
- Mydriatics
- Oxazoles
- Receptors, Adrenergic, alpha-2
- Rilmenidine
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Topics |
- Adrenergic alpha-2 Receptor Agonists
- Animals
- Cats
- Central Nervous System
(drug effects, metabolism)
- Dose-Response Relationship, Drug
- Female
- Male
- Mydriatics
(pharmacology)
- Oxazoles
(pharmacology)
- Pupil
(drug effects, physiology)
- Receptors, Adrenergic, alpha-2
(metabolism)
- Rilmenidine
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