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Mechanism of ketanserin-induced sympatho-inhibition
- Source :
- European Journal of Pharmacology. 194:161-166
- Publication Year :
- 1991
- Publisher :
- Elsevier BV, 1991.
-
Abstract
- Experiments were undertaken to determine if sympatho-inhibition produced by ketanserin is due to antagonism of central nervous system alpha 1-adrenoceptors rather than central 5-HT2 receptors and if (like prazosin) it produces sympatho-inhibition indirectly via a central (presynaptic) alpha 2-adrenoceptor mechanism. Administration of ketanserin (0.03-3.0 mg/kg i.v.) caused a dose-related depression of sympathetic-cholinergic electrodermal responses evoked by electrical stimulation of the hypothalamus in pentobarbital anesthetized cats. No effect of ketanserin was observed on electrodermal responses evoked by preganglionic sympathetic nerve stimulation nor did the more specific 5-HT2 receptor antagonist, cinanserin, produce a central sympatholytic effect at dosages up to 3 mg/kg i.v. Pretreatment with alpha 2-adrenoceptor blockers yohimbine, idazoxan, or rauwolscine significantly antagonized ketanserin-induced sympatho-inhibition. Depletion of central nervous system (CNS) monoamines totally prevented ketanserin-induced sympatho-inhibition although clonidine (30 micrograms/kg i.v.) continued to be effective. These results suggest that ketanserin acts in the CNS to reduce sympathetic reactivity by blocking alpha 1-adrenoceptors and not 5-HT2 receptors. In this regard, ketanserin appears to act in a manner similar to other alpha 1-adrenoceptor antagonists (e.g. prazosin and indoramin) by an apparent presynaptic facilitation of alpha 2-adrenoceptor mediated tonic inhibition descending from the lower brainstem.
- Subjects :
- Central Nervous System
Male
medicine.medical_specialty
Sympathetic Nervous System
Ketanserin
Hypothalamus, Posterior
Rauwolscine
Pharmacology
chemistry.chemical_compound
Sympatholytic
Internal medicine
medicine
Prazosin
Animals
Biogenic Monoamines
Adrenergic alpha-Antagonists
5-HT receptor
Cinanserin
Galvanic Skin Response
Electric Stimulation
Yohimbine
Endocrinology
chemistry
Synapses
Cats
Female
Idazoxan
medicine.drug
Subjects
Details
- ISSN :
- 00142999
- Volume :
- 194
- Database :
- OpenAIRE
- Journal :
- European Journal of Pharmacology
- Accession number :
- edsair.doi.dedup.....4347c1c00a5182fa7fe7d55a1e406ff9