Adenosine diphosphate-induced platelet activation inhibited by magnesium in a dose-dependent manner.
OBJECTIVE
To examine the hypothesis that magnesium inhibits platelet activation at concentrations equivalent to therapeutic levels.


METHODS
Fifteen subjects were enrolled: five healthy, female donors with regular, spontaneous menstrual cycles; five women with uncomplicated third-trimester pregnancies; and five preeclamptic subjects before magnesium therapy. Anticoagulated whole blood was added to tubes containing 0.5 micromol/L adenosine diphosphate (to activate platelets), HP1-1D (activation-independent platelet antibody), CD62 antibody and CD63 antibody (activation-dependent platelet antibodies), and magnesium sulfate in increasing concentrations (2-100 mg/dL). The percentage of activated platelets (CD62 or CD63 positive) was determined using three-color flow cytometric analysis. Data were analyzed using the Student t test, repeated measures analysis of variance, two-way analysis of variance, and Student-Newman-Keuls for pairwise comparison in appropriate cases. P < .05 was considered significant.


RESULTS
Adenosine diphosphate-induced platelet activation was inhibited with increasing magnesium concentration in all subjects (P < .001). Significant inhibition of CD62 and CD63 expression first occurred at a magnesium concentration of 4 mg/dL in the normal pregnant group (P < .05), at 6 mg/dL in the preeclamptic group (P < .05), and at 8 mg/dL in the nonpregnant group (P < .05).


CONCLUSIONS
Magnesium inhibits adenosine diphosphate-induced platelet activation in a dose-dependent manner. This effect initially attains statistical significance at concentrations equivalent to therapeutic levels.
Leaphart
W L
WL
Department of Biochemistry, University of Vermont, Burlington, USA.
Meyer
M C
MC
Capeless
E L
EL
Tracy
P B
PB
D000244:Adenosine Diphosphate / Q000037:antagonists & inhibitors*; D000328:Adult; D000704:Analysis of Variance; D015703:Antigens, CD / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008274:Magnesium / Q000494:pharmacology*; D019007:P-Selectin / Q000502:physiology; D015539:Platelet Activation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000502:physiology; D011247:Pregnancy; D060149:Tetraspanin 30
D015703:Antigens, CD; C554586:CD63 protein, human; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; D000244:Adenosine Diphosphate; D008274:Magnesium