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    
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.
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    
Anaesthesia and Intensive Care, Royal Adelaide Hospital/University of Adelaide, North Terrace, Adelaide, Australia.
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MeSH Terms
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*
Vascular Resistance / drug effects
Reg. No./Substance:

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

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