Document Detail


Acute cardiovascular effects of magnesium and their relationship to systemic and myocardial magnesium concentrations after short infusion in awake sheep.
MedLine Citation:
PMID:  11356944     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
D Zheng; R N Upton; G L Ludbrook; A Martinez
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
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:
Created Date:  2001-05-17     Completed Date:  2001-06-14     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1176-83     Citation Subset:  IM    
Affiliation:
Anaesthesia and Intensive Care, Royal Adelaide Hospital/University of Adelaide, North Terrace, Adelaide, Australia.
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MeSH Terms
Descriptor/Qualifier:
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:
7439-95-4/Magnesium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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