Heart angiotensin-converting enzyme activity increased after intraperitoneal bleomycin administration in rat

Angiotensin-converting enzyme (ACE) generates angiotensin II and degrades bradykinin. This ectopeptidase acts as a marker in pathologic conditions, showing tissue and vascular damage. In order to evaluate serum and tissue ACE activity in bleomycin-associated lung damage, the authors studied morphological and enzymatic alterations as well as blood pressure in male Sprague-Dawley rats. Animals were treated intraperitoneally with bleomycin (5 mg/kg) 3 times for 1 week. This subacute and therapeutic dose produced morphologically evident pulmonary damage characterized by alveolar septum thickness and collagen deposition. Bleomycin also had significantly lowered lung and aorta N-acetyl-beta-D-glucosaminidase (NAG) activity, whereas heart and serum NAG activity increased significantly. Serum ACE activity was significantly lower in the treated animals, and heart ACE activity increased significantly. Lung ACE activity and blood pressure did not change during the study. The authors conclude that heart ACE activity increased faster than pulmonary ACE and serum ACE is a good indicator of damage even in subacute therapeutic bleomycin doses.