We have studied the effects of both impaired prothrombin activation and direct inhibition of thrombin on the platelet release reaction in clotting blood to determine the role of thrombin in this process. In blood from two patients with congenital Factor V deficiency, prothrombin activation during spontaneous in vitro clotting was delayed and decreased. Secretion of platelet Factor 4 was also delayed and was detected only after thrombin formation was initiated. Addition of a small amount of normal plasma to the patients' blood in vitro corrected the abnormalities in both thrombin formation and the platelet release reaction in parallel fashion. A delay in the onset of secretion of platelet Factor 4 was also observed when thrombin generated in normal blood during spontaneous in vitro clotting was inhibited by either purified hirudin or anti-thrombin Fab. These observations suggest that thrombin is the essential stimulus for platelet secretion during in vitro blood clotting.
Marc A. Shuman
Usage data is cumulative from April 2024 through April 2025.
Usage | JCI | PMC |
---|---|---|
Text version | 126 | 2 |
43 | 16 | |
Scanned page | 232 | 2 |
Citation downloads | 53 | 0 |
Totals | 454 | 20 |
Total Views | 474 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.