Sensitivity of fatty acid cyclooxygenase from human aorta to acetylation by aspirin.

Abstract

The rate of acetylation of fatty acid cyclooxygenase (prostaglandin synthase, EC 1.14.99.1) by [acetyl-3H]-aspirin was measured in microsomes from human aortas and coronary arteries and intact and disrupted human platelets. The inhibition by aspirin of prostacyclin generation from exogenous arachidonic acid in shredded human aorta was also measured. Cyclooxygenase in human aorta and coronary artery microsomes was approximately 1/250th as sensitive to aspirin as enzymne in intact platelets, and 1/60th as sensitive to aspirin as enzyme measured in a platelet microsomal preparation. Small oral doses of aspirin are apparently sufficient to inhibit platelet prostaglandin production but are not sufficient to substantially effect aorta or coronary artery prostaglandin production.