Measurement by electrical impedance aggregometry of porcine platelets response to selected physiological agonists

Although the domestic swine is commonly employed for physiological studies of the coronary circulation, there is relatively little data available concerning the responsiveness in whole blood of normal porcine platelets to standard physiological agonists. Such information is essential if the domestic swine is to be used as an animal model for studying potential interactions between platelets and the coronary circulation. Accordingly, the present study was undertaken to characterize the responses (aggregation and ATP release) observed in whole blood of normal porcine platelets to selected physiological agonists. The responses of platelets from 10 normal human volunteers also were studied with this system for comparison. Agents tested included ADP, arachidonic acid, collagen, epinephrine, norepinephrine, and thrombin. Studies were conducted with the Chronolog impedance aggregometer. The results demonstrate that platelets of domestic swine are reactive to ADP, arachidonic acid, and collagen. In contrast, neither epinephrine nor norepinephrine alone induced aggregation or release. Norepinephrine, however, caused modest potentiation of aggregation in response to ADP only. At 1 mM concentration each catecholamine inhibited the release response to collagen while at 10 mM each inhibited aggregation and release in response to either ADP or collagen. The data obtained indicate the domestic swine may be employed as a useful model to examine interactions between platelets and the coronary circulation.