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Early thrombolysis inhibits peri-infarct depolarizations in embolic MCA occlusion
O G Schüler1, N Plesnila, D Otto
1Department of Neurology, Klinikum Grosshadern, Ludwig Maximilians-University, Marchioninistr. 15, D-81377 Munich, Germany.
Abstract:
Rats submitted to middle cerebral artery (MCA) clot embolism were treated with tissue plasminogen activator (TPA) 1.5 and 3.5 h post-occlusion. Reperfusion patterns were monitored by measuring cortical laser-Doppler flow; the direct current potential was measured to detect peri-infarct depolarizations (PID), a known mechanism of ischemic injury. TPA treatment induced reperfusion in 58% of treated animals that was delayed by 41 +/- 7 min (mean +/- s.e.m.) from treatment onset. The probability of reperfusion did not differ significantly between the two treatment groups. TPA treatment led to a 3-fold reduced frequency of PID if administered early or if successful reperfusion was observed (each p < 0.001). Early thrombolysis inhibits, but does not block, PID as an important mechanism of ischemic injury in embolic stroke.
Insights
Early administration of tissue plasminogen activator (TPA) in rats with embolic stroke reduced the frequency of peri-infarct depolarizations (PID). However, TPA did not completely block PID, indicating its role in ischemic injury.
Area of Science:
- Neuroscience
- Cerebrovascular Research
- Pharmacology
Background:
- Middle cerebral artery (MCA) occlusion in rats is a model for embolic stroke.
- Peri-infarct depolarizations (PID) are a key mechanism of ischemic brain injury.
- Tissue plasminogen activator (TPA) is a thrombolytic agent used in stroke treatment.
Purpose of the Study:
- To investigate the effect of TPA treatment timing on reperfusion and PID in a rat model of embolic stroke.
- To determine if early TPA administration influences the occurrence of PID.
Main Methods:
- Rats with MCA occlusion were treated with TPA at 1.5 and 3.5 hours post-occlusion.
- Reperfusion was monitored using laser-Doppler flowmetry.
- PID was detected by measuring direct current potential.
Main Results:
- TPA induced reperfusion in 58% of treated rats, with a delay of 41 ± 7 minutes.
- Reperfusion rates did not significantly differ between early and late treatment groups.
- TPA treatment significantly reduced PID frequency by 3-fold when administered early or when reperfusion was successful (p < 0.001).
Conclusions:
- Early thrombolysis with TPA inhibits, but does not abolish, PID in embolic stroke.
- PID remains a significant mechanism of ischemic injury even with successful reperfusion.
- Timing of TPA administration impacts PID frequency, highlighting the importance of early intervention.