| Acute cardiovascular effects of magnesium and their relationship to systemic and myocardial magnesium concentrations after short infusion in awake sheep. | |
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MedLine Citation:
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PMID: 11356944 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The temporal relationship between the systemic and myocardial concentrations of magnesium and some of its acute cardiovascular effects were examined after short i.v. infusion administration of magnesium (30 mmol over 2 min) in five awake chronically instrumented sheep. Magnesium decreased mean arterial blood pressure and systemic vascular resistance (SVR) by 23 and 41% from baseline, respectively. These hemodynamic changes were consistent with magnesium producing primary reductions in SVR with partial heart rate (HR)-mediated compensation of blood pressure. Cardiac output and HR increased by 38 and 38% from baseline, respectively. Magnesium had little effect on myocardial contractility, but substantially increased myocardial blood flow (MBF, 77% above baseline) primarily due to direct myocardial vasodilation. The peak arterial and coronary sinus serum magnesium concentrations were 6.94 +/- 0.26 (mean +/- S.E.M.) and 6.51 +/- 0.20 mM, respectively, at 2 min. Both arterial and coronary sinus magnesium concentrations at the end of the study were still more than 3 mM, whereas all the cardiovascular effects were back to baseline. The myocardial kinetics of magnesium was consistent with rapid equilibration of magnesium (half-life 0.4 min) with a small distribution volume (71 ml) consistent with the extracellular space of the heart. In conclusion, magnesium was shown to have a rapid equilibration between the plasma/serum concentrations of magnesium and its extracellular concentration in the myocardium. However, the primary cardiovascular effect of magnesium (reductions in SVR) preceded its extracellular concentrations, and was a direct function of its arterial concentration. A "threshold" model for changes in SVR was preferred when linked to the arterial magnesium concentration. |
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Authors:
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D Zheng; R N Upton; G L Ludbrook; A Martinez |
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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: The Journal of pharmacology and experimental therapeutics Volume: 297 ISSN: 0022-3565 ISO Abbreviation: J. Pharmacol. Exp. Ther. Publication Date: 2001 Jun |
Date Detail:
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Created Date: 2001-05-17 Completed Date: 2001-06-14 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0376362 Medline TA: J Pharmacol Exp Ther Country: United States |
Other Details:
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Languages: eng Pagination: 1176-83 Citation Subset: IM |
Affiliation:
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Anaesthesia and Intensive Care, Royal Adelaide Hospital/University of Adelaide, North Terrace, Adelaide, Australia. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Blood Flow Velocity / drug effects Blood Pressure / drug effects Cardiac Output / drug effects Cardiovascular Physiological Phenomena / drug effects* Cardiovascular System / drug effects* Coronary Circulation / drug effects Extracellular Space / metabolism Heart Rate / drug effects Infusions, Intravenous Magnesium / administration & dosage, metabolism*, pharmacokinetics* Models, Cardiovascular Myocardial Contraction / drug effects Myocardium / metabolism* Sheep Vascular Resistance / drug effects Wakefulness |
| Chemical | |
Reg. No./Substance:
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7439-95-4/Magnesium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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