Acute elevation and recovery of intracellular [Mg2+] following human focal cerebral ischemia.
We used 31P magnetic resonance spectroscopy (MRS) to investigate changes in brain intracellular [Mg2+] following human focal cerebral ischemia. Mean brain pMg (where pMg = -log[Mg2+]) was significantly lower in the ischemic focus of all stroke patients (pMg = 3.34 +/- 0.28, n = 45, p < 0.01) when compared with normal controls (pMg = 3.50 +/- 0.08, n = 25). Ischemic brain pMg was also significantly reduced when the pH of the stroke region was acidotic (pH < 6.90, pMg = 3.07 +/- 0.44, n = 11, p < 0.01) and when the phosphocreatine index (PCrI = PCr/[PCr+Pi (inorganic phosphate)]) was reduced (PCrI < 0.47, pMg = 3.12 +/- 0.42, n = 13, p < 0.01). Mean brain pMg was significantly reduced at days 0 to 1 (acute) poststroke (pMg = 3.32 +/- 0.28, n = 26, p < 0.01) and at days 2 to 3 (subacute) poststroke (pMg = 3.38 +/- 0.28, n = 21, p = 0.03). There was also a significant (p < 0.01) correlation between decreased pMg and increased relative signal intensity of Pi (normalized by total phosphate signal, Pi/TP) for all stroke groups studied. During the temporal evolution of stroke, pH returned to normal levels by days 2 to 3, and pMg returned to normal by days 4 to 10 (subacute). PCrI and Pi/TP returned toward normal levels after 10 days (chronic), at a time when ischemic brain pH had become significantly alkalotic (pH = 7.10 +/- 0.24, n = 15, p < 0.01). Elevation of ischemic brain [Mg2+] is temporally linked to the acidotic phase of human stroke as well as the breakdown of energy metabolism. These acute changes in [Mg2+] may contribute to, or be a marker for, cellular injury.
Helpern
J A
JA
Department of Neurology, Henry Ford Health Sciences Center, Detroit, MI 48202-2689.
Vande Linde
A M
AM
Welch
K M
KM
Levine
S R
SR
Schultz
L R
LR
Ordidge
R J
RJ
Halvorson
H R
HR
Hugg
J W
JW
D000255:Adenosine Triphosphate / Q000378:metabolism; D000368:Aged; D001921:Brain / Q000378:metabolism; D002561:Cerebrovascular Disorders / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus
D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate; D008274:Magnesium