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The Journal of Neuroscience, February 9, 2005, 25(6):1387-1394; doi:10.1523/JNEUROSCI.4182-04.2005

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Neurobiology of Disease
Peri-Infarct Depolarizations Reveal Penumbra-Like Conditions in Striatum

Masao Umegaki,^1,2 * Yasuhiro Sanada,^1,2 * Yannic Waerzeggers,¹ Gerhard Rosner,¹ Toshiki Yoshimine,² Wolf-Dieter Heiss,¹ and Rudolf Graf¹

¹Max-Planck Institute for Neurological Research, D-50931 Köln, Germany, and ²Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan

Spreading depression-like peri-infarct depolarizations not only characterize but also worsen penumbra conditions in cortical border zones of experimental focal ischemia. We intended to investigate the relevance of ischemic depolarization in subcortical regions of ischemic territories.

Calomel electrodes measured DC potentials simultaneously in the lateral and medial portions of the caudate nucleus (CN) of 11 anesthetized cats after permanent occlusion of the middle cerebral artery. Additionally, platinum electrodes measured cerebral blood flow (CBF) in the CN, and laser Doppler probes CBF in the cortex.

Depolarizations (negative DC shifts >10 mV) were obtained in 10 of 11 cats. Further differentiation revealed that short-lasting spreading depression-like depolarizations (SDs; 5 of 10 cats: 5.24 ± 1.22 min total duration; 23.3 ± 4.2 mV amplitude) were predominantly found in medial and longer depolarizations (LDs; 4 of 10 cats: 64.7 ± 47.5 min; 25.0 ± 11.3 mV) in the lateral CN. Terminal depolarizations (TDs; 6 of 10 cats; without repolarization) occurred immediately after occlusion or at later stages, being then accompanied by elevations of intracranial pressure presumably inducing secondary CBF reduction. CBF tended to be lower in regions with TDs (33.3 ± 29.9% of control) and LDs (37.3 ± 22.8%) than in regions with SDs (51.5 ± 48.0%).

We conclude that in focal ischemia, transient peri-infarct depolarizations emerge not only in cortical but also in striatal gray matter, thereby demonstrating the existence of subcortical zones of ischemic penumbra. The generation of these ischemic depolarizations is a multifocal process possibly linked to brain swelling and intracranial pressure rise in the later course of focal ischemia, and therefore a relevant correlate of progressively worsening conditions.

Key words: peri-infarct depolarization; spreading depression; focal ischemia; intracranial pressure; striatum; cat

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Received Oct 8, 2004; revised December 21, 2004; accepted December 21, 2004.

This article has been cited by other articles:

				R. M. Dietz, J. H. Weiss, and C. W. Shuttleworth Zn2+ Influx Is Critical for Some Forms of Spreading Depression in Brain Slices J. Neurosci., August 6, 2008; 28(32): 8014 - 8024. [Abstract] [Full Text] [PDF]

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