Steficek B A, Thomas J S, McConnell M F, Bell T G
Department of Pathology, Michigan State University, E. Lansing 48824.
Thromb Res. 1993 Oct 15;72(2):145-53. doi: 10.1016/0049-3848(93)90216-b.
A severe hereditary hemorrhagic diathesis in Simmental cattle has been identified in North America. Platelet numbers and coagulation profiles of affected cattle are normal. We have further characterized the severe dysfunction of platelet aggregation. All agonists tested elicited normal shape change. Aggregations in response to ADP, A23187, and collagen were absent. Aggregations were decreased or required more time for completion in response to PAF and thrombin. No ultrastructural abnormalities were observed in transmission electron micrographs. Dense granule release of ATP in response to PAF was normal. Thrombin-induced aggregation was dependent upon external calcium concentration in normal but not affected animals. Clot retraction in the blood from affected animals was abnormal. The data implicate a defect of Ca++ mobilization or utilization.
