| Evidence for multiple adrenoceptor sites in rainbow trout vasculature. | |
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MedLine Citation:
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PMID: 8071465 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The importance of neuronal and lumenal vascular adrenoceptors in the regulation of vascular reactivity was examined in rainbow trout (Oncorhynchus mykiss), in vivo and in vitro. In vivo, ganglionic blockade with hexamethonium or alpha-adrenoceptor blockade, with either phentolamine or prazosin, produced similar (7mmHg) decreases in dorsal aortic blood pressure. The drop in dorsal aortic pressure produced by phentolamine or prazosin was due to reduced systemic vascular resistance. Neither the alpha-adrenoceptor antagonist, phenoxybenzamine nor chemical sympathectomy with 6-hydroxy-dopamine affected dorsal aortic pressure. However, after chemical sympathectomy, phenoxybenzamine lowered dorsal aortic pressure to levels similar to that produced by either phentolamine or prazosin. Plasma epinephrine and norepinephrine concentrations increased four- and twofold, respectively, in sympathectomized fish. Sympathectomy also produced a leftward shift in the epinephrine dose/response curve of the in vitro perfused splanchnic vasculature, placing the effective catecholamine concentration well within the in vivo plasma levels. These results indicate that following chemical sympathectomy arterial blood pressure is stabilized by circulating catecholamines through the combined effect of increased plasma catecholamine concentrations and increased sensitivity of vascular adrenoceptors. Phenoxybenzamine is incapable of blocking neuronal vascular adrenoceptors but is a potent antagonist of the up-regulated adrenoceptors, suggesting that the latter are localized on the lumenal side of the vessel. |
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Authors:
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H Y Xu; K R Olson |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Volume: 163 ISSN: 0174-1578 ISO Abbreviation: J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol. Publication Date: 1993 |
Date Detail:
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Created Date: 1994-09-28 Completed Date: 1994-09-28 Revised Date: 2009-06-08 |
Medline Journal Info:
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Nlm Unique ID: 8413200 Medline TA: J Comp Physiol B Country: GERMANY |
Other Details:
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Languages: eng Pagination: 470-6 Citation Subset: IM |
Affiliation:
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Indiana University School of Medicine, South Bend Center, University of Notre Dame, IN 46556. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Pressure / drug effects* Epinephrine / blood, pharmacology Hexamethonium Compounds / pharmacology Oncorhynchus mykiss / blood, physiology* Phenoxybenzamine / pharmacology Phentolamine / pharmacology Prazosin / pharmacology Receptors, Adrenergic / drug effects, physiology* Sympathectomy, Chemical |
| Chemical | |
Reg. No./Substance:
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0/Hexamethonium Compounds; 0/Receptors, Adrenergic; 19216-56-9/Prazosin; 50-60-2/Phentolamine; 51-43-4/Epinephrine; 59-96-1/Phenoxybenzamine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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