In an attempt to develop an animal model for the study of the effects of fluid shear stress on platelet in vivo survival we examined the effects of repetitive short-duration (5 sec) and continuous prolonged (5 min) shear exposure in a cone-plate viscometer and Couette rotational viscometer on platelets (in citrated platelet-rich plasma) from humans, rabbits, dogs, and pigs. Comparable platelet aggregation (PAG = loss of single platelets) (18-64%) was observed with platelets from all species, associated with dense granule release, as a function of shear stress amplitude (25-50 dyn/cm2) under the conditions used. However, whereas with human platelets, little or no platelet injury (loss of LDH) was observed, appreciable platelet LDH loss was found with platelets from all animal species studied even at the lowest shear stress used, and LDH loss progressively increased with increasing shear stress amplitude (up to 30% at 50 dyn/cm2), and duration both in the cone-plate and Couette viscometer. These findings indicate a fundamental difference in the response of rabbit, dog, and pig platelets (as compared to that of human platelets) to laminar fluid shear stress in vitro. The mechanism(s) and factors leading to the apparent increased mechanical fragility of the animal platelets as compared to human platelets are currently under investigation.
Fluid shear stress-induced cytosolic calcium signalling and degranulation dynamics in mast cells