Plasma Chymase Activity Reflects the Change in Hemodynamics Observed after the Surgical Treatment of Patent Ductus Arteriosus in Dogs

SIMPLE SUMMARY: Chymase is a type of protease associated with tissue injury, inflammation, and the remodeling of the cardiovascular system. Chymase has been suspected to increase with the progression of cardiovascular diseases. The measurement of chymase activity can only be taken at the time of cardiovascular failure and requires tissue sampling. Therefore, chymase has not been examined in both human and veterinary medicine. In the present study, chymase activity was measured by using plasma from dogs diagnosed with patent ductus arteriosus, a commonly observed congenital heart disease condition in dogs. Moreover, as patent ductus arteriosus can be treated surgically, chymase activity was also measured in the post-operation plasma. The results of the present study showed that chymase activity could be measured from plasma in dogs with patent ductus arteriosus, and a decreased chymase activity was observed with an improvement in hemodynamics due to the surgical treatment. These new findings provide important information about the chymase mechanism in the field of veterinary medicine. In the future, chymase activity may be necessary for routine examinations of cardiac disorders in veterinary medicine. ABSTRACT: Chymase is a protease stored in mast cell granules that produces angiotensin II (ANG II) from angiotensin I (ANG I) and is associated with tissue injury, inflammation, and remodeling, especially involving the cardiovascular system. As cardiovascular events occur, chymase is activated by degranulation to the extracellular matrix. Although chymase has been suggested to be associated with cardiovascular disease progression, there are not enough reports in veterinary medicine. Patent ductus arteriosus (PDA) is a common congenital cardiac disease in veterinary medicine. Almost all cases of PDA can be treated surgically to prevent the development of congestive heart disease and/or pulmonary hypertension. The aims of the present study were to measure chymase activity before and after PDA occlusions, and to investigate the relationships between the congestive and hemodynamic states of PDA and chymase activity. In the present study, 17 puppies diagnosed with PDA were included and all puppies completely recovered to the level of healthy dogs. Chymase activity significantly decreased at 2 months after the operation, along with the echocardiography parameters of congestion. Therefore, plasma chymase activity may be useful as a novel predictor for understanding the hemodynamics of PDA in veterinary medicine.