Effects of magnesium sulfate on pentylenetetrazol-induced status epilepticus.
The use of magnesium sulfate (MgSO4) as an anticonvulsant is controversial. Status epilepticus was induced in 0.5% halothane-anesthetized Wistar rats with a threshold (90 mg/kg) or suprathreshold (200 mg/kg) dose of intravenous (i.v.) pentylenetetrazol (PTZ) under stereotactic hippocampal depth electrode monitoring. Fifteen minutes after seizure induction, the maximum hemodynamically tolerated dose of MgSO4 (10 mg/kg/min in 22 min) was administered i.v. MgSO4 was ineffective in altering seizure discharge. A subgroup of nine animals received hypertonic mannitol before MgSO4 to open the blood-brain barrier (BBB) to facilitate Mg2+ CNS penetration. Again MgSO4 was ineffective in attenuating epileptic activity. These results support the contention that MgSO4 is not an effective treatment for status epilepticus. We hypothesize that because Mg2+ blocks Ca2+ influx into the neuron through the N-methyl-D-aspartate (NMDA) receptor-operated calcium channel in a voltage-dependent manner it would be ineffective in neurons that are continuously depolarizing as in status epilepticus.
Link
M J
MJ
Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota 55905.
Anderson
R E
RE
Meyer
F B
FB
D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D002118:Calcium / Q000037:antagonists & inhibitors; D004569:Electroencephalography / Q000187:drug effects; D006982:Hypertonic Solutions; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D008274:Magnesium / Q000494:pharmacology; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008353:Mannitol / Q000008:administration & dosage / Q000494:pharmacology; D010433:Pentylenetetrazole / Q000008:administration & dosage; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D013226:Status Epilepticus / Q000139:chemically induced* / Q000188:drug therapy / Q000503:physiopathology
D006982:Hypertonic Solutions; D016194:Receptors, N-Methyl-D-Aspartate; D008353:Mannitol; D008278:Magnesium Sulfate; D008274:Magnesium; D002118:Calcium; D010433:Pentylenetetrazole