Low dose aspirin, platelet function and prostaglandin synthesis: influence of epinephrine and alpha adrenergic blockade.
The present investigation has evaluated the effects of low doses of oral aspirin on platelet prostaglandin synthesis and function. Whole (80 mg) or half (40 mg) tablets of baby aspirin given to adults had no effect on the response of their platelets to thrombin, ADP and epinephrine, but selectively inhibited aggregation induced by threshold concentrations of arachidonate 16-20 hours after ingestion. Larger amounts of arachidonate overcame the inhibition imposed by low dose aspirin, but not by adult aspirin tablets (600 mg). Epinephrine, in concentrations too low to cause aggregation, restored the sensitivity of aspirin-treated platelets to arachidonate. Studies with alpha-adrenergic agonists, antagonists and calcium channel blockers demonstrated that the corrective effect of epinephrine was mediated by an alpha-adrenergic receptor influence on calcium modulation of the platelet membrane.
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology*; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010974:Platelet Aggregation / Q000187:drug effects*; D011453:Prostaglandins / Q000096:biosynthesis*; D013917:Thrombin / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D001095:Arachidonic Acids; D011453:Prostaglandins; D000244:Adenosine Diphosphate; D013917:Thrombin; D001241:Aspirin; D002118:Calcium; D004837:Epinephrine