B

Inhibition of platelet aggregation by ASA is due to a selective blockade of platelet cyclooxygenase (B). Selectivity of this action results from acetylation of this enzyme during the initial passage of the platelets through splanchnic blood vessels. Acetylation of the enzyme is irreversible. ASA present in the systemic circulation does not play a role in platelet inhibition. Since ASA undergoes extensive presystemic elimination, cyclo-oxygenases outside platelets, e.g., in en-dothelial cells, remain largely unaffected. With regular intake, selectivity is enhanced further because the anuclear platelets are unable to resynthesize new enzyme and the inhibitory effects of consecutive doses are added to each other. However, in the endothelial cells, de novo synthesis of the enzyme permits restoration of prostacyclin production.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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