Abstract
During operations, neurosurgeons usually perform multiple temporary occlusions of parental artery, possibly resulting in the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this study, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion (VO) model to compare between single occlusion and repeated transient occlusions within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. From real time monitoring of glutamate release in 11 VO model, the change of extracellular glutamate level in repeated transient occlusion group was smaller than that of single occlusion group, and the onset time of glutamate release in the second ischemic episode of repeated occlusion group was delayed compared to the first ischemic episode which was similar to that of single 10 min ischemic episode. These results suggested that repeated transient occlusion induces less glutamate release from neuronal cell than single occlusion, and the delayed onset time of glutamate release is attributed to endogeneous protective mechanism of ischemic tolerance.
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Fig. 1.
Vascular anatomy of the neck dissection at left side. A, occipital artery; B, ascending pharyngeal artery; C, superior thyroid artery; D, pterygopalatine artery; ECA, external carotid artery; CCA, common carotid artery; ICA, internal carotid artery.
![kjpp-13-23f1.tif](/upload/SynapseXML/0067kjpp/thumb/kjpp-13-23f1.gif)
Fig. 3.
Real-time measurement of glutamate release and CBF during repeated 5 min transient ischemic episode.
![kjpp-13-23f3.tif](/upload/SynapseXML/0067kjpp/thumb/kjpp-13-23f3.gif)
Table 1.
The changes of glutamate concentration in 11 VO method during single 10 min occlusion and repeated 5 min occlusion
n=6 | Single occlusion group (mean±S.E.M.) | Repeated transient occlusion group | |
---|---|---|---|
First 5 min occlusion (mean±S.E.M.) | Second 5 min occlusion (mean±S.E.M.) | ||
Onset time of glutamate release (sec) | 113.16±13.07 | 108.01±11.73 | 132.74±3.03∗ |
Maximum change of glutamate release (μM) | 125.01±3.74 | 103.52±7.25∗∗ | 88.49±4.77∗∗∗ |
Total amount of glutamate release | 38,390.44±2,252.86 | 11,021.56±2,596.68∗∗∗ | 9,689.06±2,622.65∗∗∗ |