Magnesium (Mg) has been shown to reduce platelet aggregation both in vitro
and ex vivo, and this antiplatelet effect may be advantageous in the preven
tion of arterial thrombosis. Previous animal studies have shown an antithro
mbotic effect of Mg also in vivo, but mainly with higher Mg concentrations
(similar to 3.0-4.0 mM). The objectives of the present study were to evalua
te the antithrombotic effect of (1) intravenous Mg at a lower and clinicall
y more relevant concentration and (2) topically applied Mg. The study compr
ised 30 male rats, randomly assigned into 3 groups: (1) placebo group, (2)
intravenous Mg group, and (3) topical Mg group. A thrombogenic lesion was e
stablished by making a standardised arteriotomy in the right femoral artery
. The vessel was transilluminated and thrombus formation was visualised dyn
amically by in vivo microscopy and recorded on videotapes. Thrombus area wa
s measured after ended experiment by computer-assisted image analysis. Intr
avenously administered Mg, elevating the S-Mg level to 2.2 mmol/L, signific
antly reduced the mean thrombus area (p<0.05) compared to the control group
. Topically applied Mg significantly decreased the maximum thrombus area, w
ithout any increase in S-Mg level (p<0.05), The Mg-treated groups showed no
increase in bleeding complications. A transient fall in blood pressure was
seen in the systemic Mg group, but blood pressures were not significantly
different between any of the groups at the end of the experiment. In conclu
sion, topically as well as intravenously infused Mg reduce arterial thrombu
s formation in this in vivo rat model without compromising haemostasis, (C)
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