[The endothelium and antithrombotic substances].

Area of Science:

• Biochemistry
• Pharmacology
• Cardiovascular Physiology

Context:

• Thrombin, a key coagulation factor, influences hemostasis and vascular tone.
• Thrombin's vascular effects are concentration-dependent and involve endothelium-derived relaxing factor.
• Ischemic conditions can exacerbate thrombin-induced vascular responses.

Purpose:

• To investigate the vascular effects of thrombin in canine coronary arteries.
• To compare the inhibitory mechanisms of heparin and hirudin on thrombin's vascular actions.
• To evaluate recombinant hirudin as a potential therapeutic agent for thrombin-induced vasospasm.

Summary:

• Thrombin induces endothelium-dependent relaxations at lower concentrations and contractions at higher concentrations in canine coronary arteries.
• Heparin and hirudin inhibit thrombin's vascular effects through distinct binding mechanisms.
• Recombinant hirudin acts as a selective thrombin antagonist without affecting vascular smooth muscle tone or causing bleeding.

Impact:

• Thrombin plays a dual role in vascular function, mediating both relaxation and contraction.
• Understanding thrombin's interaction with the vasculature is crucial for managing cardiovascular diseases.
• Recombinant hirudin shows promise as a targeted therapy for coronary vasospasm, potentially improving outcomes in heart disease patients.