Abstract
Background and Purpose - Activation of plasma protein C (PC) zymogen by thrombin-thrombomodulin at the endothelial surface is an important endogenous antithrombotic mechanism. It is unknown whether activated protein C (APC) is generated in vivo in the cerebrovasculature, because there is only limited thrombomodulin expression in human brain vascular endothelium. Therefore, we tested the hypothesis that carotid occlusion produces brain-specific PC activation. Methods - Blood samples were simultaneously collected from the ipsilateral internal jugular vein and radial artery before and during carotid cross-clamping and on 'de-occlusion' in 8 awake patients undergoing routine carotid endarterectomy. Plasma PC zymogen and circulating APC levels were measured using enzyme immunocapture assay and expressed as percent of pooled plasma controls. Results - Internal jugular vein APC levels increased 28% exclusively during carotid occlusion and then decreased 32% with de-occlusion (F=8.1, P<0.005). PC zymogen increased only 5.9% with occlusion (F=6.3, P<0.02), consistent with hemoconcentration. There were no changes in radial artery PC or APC levels. Conclusions - These findings demonstrate brain- specific protein C activation in humans during carotid occlusion and suggest a protective role for endogenous APC generation during cerebrovascular occlusion.
Original language | English (US) |
---|---|
Pages (from-to) | 542-545 |
Number of pages | 4 |
Journal | Stroke |
Volume | 30 |
Issue number | 3 |
DOIs | |
State | Published - Mar 1999 |
Externally published | Yes |
Keywords
- Cerebral ischemia
- Protein C
- Stroke
- Thrombomodulin
ASJC Scopus subject areas
- Clinical Neurology
- Cardiology and Cardiovascular Medicine
- Advanced and Specialized Nursing