Intraoperative enzyme-amperometric monitoring of extracellular glutamate concentration with a dialysis electrode in ischemic human brain.
Changes in the extracellular concentration of glutamate in the brain ([Glu]e) were monitored continuously by an enzyme-amperometric technique employing a dialysis electrode during ischemia caused by isolation of the brain tissue in rats and human patients. In the rat (n = 10), the dialysis electrode was placed in the frontal cortex and the frontal lobe was transected. A transient sharp increase in [Glu]e was frequently observed during the transection. A biphasic elevation (a rapid increase followed by a slowly continuing increase) subsequently occurred with a latent period of 1-3 min after the transection of the rat frontal lobe. In patients (n = 7), the dialysis electrode was placed in tumor-free cortical areas which were planned to be resected together with gliomas. Progressive increases in [Glu]e were observed in all of the patients as the isolation of the brain tissue progressed. A biphasic increase, similar to that seen in the rat, was identified in 2 patients in whom the cortical area surrounding the dialysis electrode was rapidly isolated. The present enzyme-amperometric technique employing a dialysis electrode appears to be useful for detecting the occurrence of potentially harmful ischemia and for securing minimal metabolic stress caused during various surgical manipulations.
Kawamata
T
T
Department of Neurological Surgery, Nihon University, School of Medicine, Tokyo, Japan.
Katayama
Y
Y
Satoh
M
M
Mori
T
T
Maeda
T
T
D000818:Animals; D002545:Brain Ischemia / Q000201:enzymology* / Q000601:surgery; D004567:Electrodes, Implanted; D004594:Electrophysiology / Q000379:methods; D005110:Extracellular Space / Q000737:chemistry*; D005625:Frontal Lobe / Q000201:enzymology* / Q000502:physiology* / Q000601:surgery; D018698:Glutamic Acid / Q000032:analysis* / Q000378:metabolism*; D006801:Humans; D017551:Microdialysis / Q000379:methods*; D016343:Monitoring, Intraoperative; D010088:Oxidoreductases / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D018698:Glutamic Acid; D010088:Oxidoreductases