Platelet prostacyclin binding in coronary artery disease

Area of Science:

• Cardiovascular Medicine
• Platelet Physiology
• Thrombosis Research

Background:

• Reduced platelet responsiveness to prostacyclin is linked to coronary artery disease, potentially causing thrombosis and vasospasm.
• Enhanced in vivo release of cyclic endoperoxides and thromboxane A2 by platelets may contribute to this reduced responsiveness.

Purpose of the Study:

• To investigate specific prostacyclin binding to platelets in patients with coronary artery disease.
• To examine the effects of prostacyclin on platelet aggregation and cyclic adenosine monophosphate (cyclic AMP) accumulation.

Main Methods:

• Direct binding studies using 9-3H-prostacyclin sodium salt to measure prostacyclin binding to intact platelets.
• Assessed prostacyclin's inhibitory effect on adenosine diphosphate-induced platelet aggregation.
• Measured prostacyclin-induced cyclic AMP accumulation in platelets.

Main Results:

• Platelet prostacyclin binding capacity, affinity, and cyclic AMP accumulation were similar in stable angina patients and controls.
• Patients with acute myocardial infarction showed significantly reduced prostacyclin receptor binding capacity.
• Post-receptor response, including prostacyclin-induced cyclic AMP synthesis, was impaired in acute myocardial infarction patients.

Conclusions:

• Impaired platelet prostacyclin receptor binding and signaling are evident in acute myocardial infarction.
• These findings suggest a potential mechanism contributing to coronary thrombosis in heart attack patients.
• Heparin, nitroglycerin, and L-epinephrine did not interfere with prostacyclin binding in vitro.