Study of Serum and Tissues Angiotensin Converting Enzyme (ACE) Activity in Rat with Gentamicin Induced Renal Toxicity

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Short Term Change of Urinary N-Acetyl-.BETA.-D-Glucosaminidase in Reduced Kidney Mass with Renal Artery Ligation

The aim of the present study was to evaluate short term urinary NAG levels in a model of reduced kidney mass. The half and quarter kidney mass were made from ligation of the renal artery. Both groups decreased in the level of excreted NAG on day 1 and 2 after operation. On day 5 after operation, both groups achieved urinary enzyme levels comparable to that of the sham-operated group. The remaining compensated nephrons held normal range of excreted urinary NAG levels, although reduced number of nephrons resulted in a decline in urinary NAG levels.

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.