Acute cardiovascular effects of magnesium and their relationship to systemic and myocardial magnesium concentrations after short infusion in awake sheep

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dc.contributor.authorZheng, D.
dc.contributor.authorUpton, R.
dc.contributor.authorLudbrook, G.
dc.contributor.authorMartinez, A.
dc.date.issued2001
dc.descriptionCopyright © 2001 by The American Society for Pharmacology and Experimental Therapeutics
dc.description.abstractThe 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.
dc.identifier.citationJournal of Pharmacology and Experimental Therapeutics, 2001; 297(3):1176-1183
dc.identifier.doi10.1016/s0022-3565(24)29648-8
dc.identifier.issn0022-3565
dc.identifier.issn1521-0103
dc.identifier.orcidUpton, R. [0000-0001-9996-4886]
dc.identifier.orcidLudbrook, G. [0000-0001-6925-4277]
dc.identifier.urihttp://hdl.handle.net/2440/14749
dc.language.isoen
dc.publisherAmer Soc Pharmacology Experimental Therapeutics
dc.source.urihttps://doi.org/10.1016/s0022-3565(24)29648-8
dc.subjectMyocardium
dc.subjectCardiovascular System
dc.subjectExtracellular Space
dc.subjectAnimals
dc.subjectSheep
dc.subjectMagnesium
dc.subjectBlood Flow Velocity
dc.subjectCardiac Output
dc.subjectInfusions, Intravenous
dc.subjectWakefulness
dc.subjectBlood Pressure
dc.subjectHeart Rate
dc.subjectVascular Resistance
dc.subjectCoronary Circulation
dc.subjectMyocardial Contraction
dc.subjectModels, Cardiovascular
dc.subjectCardiovascular Physiological Phenomena
dc.titleAcute cardiovascular effects of magnesium and their relationship to systemic and myocardial magnesium concentrations after short infusion in awake sheep
dc.typeJournal article
pubs.publication-statusPublished

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