| Effects of NG-nitro-L-arginine methyl ester on regional haemodynamic responses to MgSO4 in conscious rats. | |
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MedLine Citation:
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PMID: 8012714 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. We assessed regional haemodynamic responses to the vasodilator, MgSO4, in the absence and presence of the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), in conscious chronically instrumented Long Evans rats (n = 9). 2. MgSO4 (loading dose 220 mumol kg-1 min-1 for 7 min, maintenance dose 56 mumol kg-1 min-1 for 7 min), alone, caused slight bradycardia and hypotension accompanied by reductions in renal and mesenteric flows, but a marked hyperaemic vasodilatation in the hindquarters (flow, delta 54 +/- 6%, vascular conductance, delta 77 +/- 5%). 3. L-NAME (183 nmol kg-1 min-1) caused hypertension (29 +/- 2 mmHg) accompanied by bradycardia (-51 +/- 6 beats min-1) and reductions in flow and vascular conductance in the renal (-18 +/- 4% and -35 +/- 3%, respectively), mesenteric (-35 +/- 3% and -49 +/- 3%, respectively), and hindquarters (-26 +/- 3% and -42 +/- 3%, respectively) vascular beds. In the presence of L-NAME, the hypotensive and bradycardic effects of MgSO4 were still apparent, but its hindquarters hyperaemic vasodilator effect was significantly attenuated. 4. In order to determine if the inhibitory action of L-NAME on the hindquarters hyperaemic vasodilator action of MgSO4 was a non-specific effect, due to the change in baseline conditions caused by L-NAME, we also examined responses to MgSO4 in the presence of endothelin-1 (12.5 pmol kg-1 min-1) or angiotensin II (50 pmol kg-1 min-1). In the presence of either peptide, the overall effects of MgSO4 on hindquarters flow and vascular conductance were unchanged. 5. In a separate experiment (n = 8) we determined that the inhibitory effect of L-NAME on the hyperaemic vasodilator response to MgSO4 was prevented by L-arginine, and also demonstrated that the Beta2-adrenoceptor antagonist, ICI 118551, caused significant inhibition of the hindquarters haemodynamic effects of MgSO4.6. We conclude that the hindquarters haemodynamic effects of MgSO4 in conscious rats involve a substantial L-NAME-sensitive component which depends on activation of Beta2-adrenoceptors, probably asa consequence of adrenal medullary adrenaline release. |
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Authors:
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P A Kemp; S M Gardiner; J E March; T Bennett; P C Rubin |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: British journal of pharmacology Volume: 111 ISSN: 0007-1188 ISO Abbreviation: Br. J. Pharmacol. Publication Date: 1994 Jan |
Date Detail:
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Created Date: 1994-07-25 Completed Date: 1994-07-25 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 7502536 Medline TA: Br J Pharmacol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 325-31 Citation Subset: IM |
Affiliation:
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Department of Physiology & Pharmacology, University of Nottingham Medical School, Queen's Medical Centre. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Angiotensin II
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pharmacology Animals Arginine / administration & dosage, analogs & derivatives*, pharmacology Blood Pressure / drug effects Drug Interactions Drug Synergism Endothelins / pharmacology Heart Rate / drug effects Hemodynamics / drug effects* Magnesium Sulfate / pharmacology* Male Mesenteric Arteries / drug effects NG-Nitroarginine Methyl Ester Nitric Oxide / antagonists & inhibitors* Propanolamines / pharmacology Rats Receptors, Adrenergic, beta / drug effects* Renal Artery / drug effects Vascular Resistance / drug effects Vasodilation / drug effects |
| Chemical | |
Reg. No./Substance:
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0/Endothelins; 0/Propanolamines; 0/Receptors, Adrenergic, beta; 10102-43-9/Nitric Oxide; 11128-99-7/Angiotensin II; 50903-99-6/NG-Nitroarginine Methyl Ester; 72795-19-8/ICI 118551; 74-79-3/Arginine; 7487-88-9/Magnesium Sulfate |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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