Autocoids (Histamine and Serotonin)
Aspirin in low doses produces long lasting inhibition of platelet cyclooxygenase because (LQ)
|A||Platelet contain low quantity of COX|
|B||Platelets cannot synthesize fresh COX molecules|
|C||Platelets bind aspirin with high affinity|
|D||Platelet COX is inducible|
Aspirin in low doses irreversibly inhibits COX enzyme in platelets and the endothelium. Platelets lack nucleus and thus cannot regenerate COX whereas endothelium can synthesize fresh enzyme. Net effect of this process is the inhibition of platelet cox and thus, TXA2 synthesis. Low TXA2level results in the anti-aggregation of platelets.