Low levels of serum ionized magnesium are found in patients early after stroke which result in rapid elevation in cytosolic free calcium and spasm in cerebral vascular muscle cells.
Ninety-eight patients admitted to the emergency rooms of three urban hospitals with a diagnosis of either ischemic stroke or hemorrhagic stroke exhibited early and significant deficits in serum ionized Mg2+ (IMg2+), but not total Mg, as measured with a unique Mg2+-sensitive ion-selective electrode. Twenty-five percent of these stroke patients exhibited >65% reductions in the mean serum IMg2+ found in normal healthy human volunteers or patients admitted for minor bruises, cuts or deep lacerations. The stroke patients also demonstrated significant elevation in the serum ionized Ca2+ (ICa2+)/IMg2+ ratio, a sign of increased vascular tone and cerebrovasospasm. Exposure of primary cultured canine cerebral vascular smooth muscle cells to the low concentrations of IMg2+ found in the stroke patients, e.g. 0.30-0.48 mM, resulted in rapid and marked elevations in cytosolic free calcium ions ([Ca2+]i) as measured with the fluorescent probe, fura-2, and digital image analysis. Coincident with the rise in [Ca2+]i, many of the cerebral vascular cells went into spasm. Reintroduction of normal extracellular Mg2+ ion concentrations failed to either lower the [Ca2+]i overload or reverse the rounding-up of the cerebral vascular cells. These results suggest that changes in Mg2+ metabolism play important roles in stroke syndromes and in the etiology of cerebrovasospasm associated with cerebral hemorrhage.
Altura
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BT
Department of Physiology, State University of New York, Health Science Center at Brooklyn, 11203, USA.
Memon
Z I
ZI
Zhang
A
A
Cheng
T P
TP
Silverman
R
R
Cracco
R Q
RQ
Altura
B M
BM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001488:Basilar Artery / Q000378:metabolism; D015415:Biomarkers / Q000097:blood; D002545:Brain Ischemia / Q000097:blood; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002536:Cerebral Arteries / Q000378:metabolism; D002543:Cerebral Hemorrhage / Q000097:blood; D002561:Cerebrovascular Disorders / Q000097:blood*; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D004563:Electrochemistry; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity
D015415:Biomarkers; D003470:Culture Media; D008274:Magnesium; D002118:Calcium