Platelet function in calves: a study of adhesion, aggregation, release, clotting factor activity and life span

Abstract

Normal calf platelets were found to significantly differ human platelets in a number of important respects. The average calf platelet count is more than twice the average human value. Calf platelets demonstrated no adhesion to glass, in a test in which over 50% of human platelets adhered. Responsiveness to several aggregating, agents, including ADP, thrombin and collagen, was markedly diminished in the calf platelet, requiring much higher concentrations of the stimulating agent to produce comparable responses. In addition, calf platelet clot-promoting activity was far less effective than with human platelets following stimulation with Celite or Russell's viper venom, although the total platelet factor 3 content exceeded that found in human paltelets, following complete disruption. In addition, the calf platelet has a significantly shorter life span and higher turnover rate than the human. These species differences in normal platelet function must be considered in evaluating the results of experiments with artificial organs in the calf model.