Hypertension , Meniere's syndrome , Obstructive thromboangiitis ( Burger's disease ) Kallidinogenase is an in vivo proteolytic enzyme involved in the regulation of blood flow and acts on kininogen to release kinin . The resulting kinin acts on the B2 receptor, releasing physiologically active substances such as NO, which inhibits vascular smooth muscle function, and PGl2 , which inhibits blood clotting .