Activation of vascular thrombin receptors mediates cardiac response to alpha-thrombin in isolated, perfused guinea pig heart

Alpha thrombin affects the constriction of arterial vessels and decreases the activity of the left ventricle. The detection of a peptide that simulates the effects of alpha thrombin indicates the presence of a protein-activated receptor. The reduction in ventricular activity is also caused by a thrombin activating protein (SFLLRN) that is similar to alpha thrombin. SFLLRN also exhibits vasoactive characteristics that is not inhibited by the inhibitory protein called hirudin. Cromakalim vasodilators are also inhibited by the effects of alpha thrombin and SFLLRN.