COMPARISON OF THE EFFECTS OF DILTIAZEM AND ASPIRIN ON PLATELET-AGGREGATION IN CATS

Platelet aggregation in response to collagen (1 or 3 mu g/ml), arachid onic acid (10(-2) M), and adenosine diphosphate (ADP, 2 mu M) was comp ared in healthy cats treated with diltiazem (approximately 2 mg/kg bod y weight, q 8 hrs for 10 doses), aspirin (approximately 21 mg/kg body weight [1 baby aspirin], q 72 hrs for three doses), or a combination o f diltiazem and aspirin. Baseline values obtained prior to treatment s erved as controls. Addition of arachidonic acid to blood resulted in a n impedance change (i.e., aggregation) with time in samples from the n ontreated cats and the cats treated with diltiazem, but the addition h ad no effect in blood from cats treated with aspirin alone or with a c ombination of diltiazem and aspirin. Platelet aggregation in response to either concentration of collagen or to ADP was not altered by any t reatment, Secretion of adenosine triphosphate (ATP) from the platelets was measured when the aggregating agent was 3 mu g/ml collagen; secre tion was not affected by any treatment.