Effects of Angiotensin Converting Enzyme Inhibition into Apoptosis and Related Genes in the Neonatal Rat Kidney

PURPOSE: The renin-angiotensin system plays an important role in renal growth and development. Exposuring the neonate to angiotensin converting enzyme(ACE) inhibitor increases mortality and results in growth retardation and abnormal renal development. ACE inhibition in the developing kidney reduces the renal expression of TGF-beta1 and EGF, which may account for renal growth impairment. This study was designed to investigate the relationship between this growth impairment, and apoptosis, cell proliferation, bcl-2 and clusterin expression. METHODS: Newborn rat pups were treated with enalapril(30mg/kg/d) or vehicle for 7 days and kidneys were removed for RT-PCR and Western blotting of bcl-2 and clusterin. Distribution of apoptosis was determined by modified TUNEL technique and PCNA for cell proliferation was stained by immunohistochemistry. RESULTS: Enalapril treatment resulted in 24% mortality by day 7 and reduced body weight(P< 0.05 versus vehicle group). Enalapril increased renal apoptosis and decreased PCNA positive proliferating cells especially in cortical tubular epithelial cells(P<0.05). Renal bcl-2 and clusterin mRNA expression was increased(P<0.05), but bcl-2 and clusterin protein expression was decreased by enalapril treatment. CONCLUSION: These results indicate that ACE inhibition in the developing kidney increases apoptosis and decreases cell proliferation, which may account for renal growth impairment. Bcl-2 and clusterin mRNA expression may increase as a secondary response to increased apoptosis and decreased their protein expression.

Kidney-Specific Regulation by Angiotensin II / 대한신장학회잡지

Angiotensin II(ANG II) plays an important role in the regulation of systemic and renal hemodynamics, and functions as a growth factor in various tissues. ANG II is also known to be associated with healing after tissue injuries as profibrotic molecule. To determine effects of ANG II itself on kidney and to know its mechanism of action, 36 adult male Sprague-Dawley rats were infused with ANG II at a dose of 50ng/min(low ANG group), 100ng/min(high ANG group), or vehicle(control group) for 1 week using osmotic minipump(Model 2001D, Alza Co, USA) inserted into the interscapular area of the back. Tissue fibrosis was quantitated morphometrically using point detection method after Masson-Trichrome stain. Expression of ED-1 was determined by immunohistochemical staining. Immunohistochemical stain, RT- PCR, and Western blot assay were done for TGFbeta1 mRNA and protien. Results were as follows:1) There were no differences in body weight or kidney weight/body weight among 3 groups. 2) Interstitial volume was increased significantly in the low and high ANG groups compared with the control group(P<0.05) 3) ED-1 positive cells were increased significantly in the the low and high ANG groups compared with the control group(P<0.05). 4) TGFbeta1 mRNA and protein expression were increased significantly in the low and high ANG groups compared with the control group(P<0.05). Therefore, regardless of systemic hypertension, ANG II infusion induced renal fibrosis and increased expression of TGFbeta1 mRNA and protein in the kidney of the Sprague-Dawley rat.

Expression of Clusterin by Angiotensin II Infusion in the Kidney and the Heart of Rats

PURPOSE: Clusterin is a heterodimeric glycoprotein and its expression is related with tissue injury and apotosis. Angitensisn II(ANG II) is known to be associated with the progression of renal disease by inducing renal fibrosis and cell proliferation. This study was designed to investigate the relationship between ANG II and clusterin expression in the kindey and the heart. We also attempted to discriminate the effect of ANG II-mediated hypertension by experimenting with two doses of ANG II-one is high enough to cause hypertension, and the other is not. METHODS: Three groups of Sprague-Dawley rats received ANG II infusion by osmotic minipump at a dose of 50ng/min, 100ng/min and placebo infusion, respectively. After 7 days, their kidneys and hearts were harvested and underwent immunohistochemical staining, RT-PCR, and Western blotting of clusterin. RESULTS: There were no differences in body weight nor organ weight/body weight among the three groups. Blood pressures of control and low-dose ANG group were not changed throughout the study, but that of high-dose ANG group was increased significantly at day 3 and 7. Staining for renal clusterin was diffusely distributed over the cortex and medulla in all 3 groups, but the intensity of staining was different notably in the medulla of control group which showed stronger staining than the ANG II infused groups. Staining intensity was not significantly different between the low and high ANG groups in the heart and kidney. In the kidney, expression of clusterin mRNA and protein were decreased in low-and high-dose ANG groups compared with control. In the heart, expression of clusterin mRNA was decreased in the low- and high-dose ANG groups compared with control. CONCLUSION: We conclude that ANG II decreases clusterin expression in the kidney and heart regardless of systemic hypertension induced by ANG II.

Angiotensin Converting Enzyme Inhibition Decreases Growth Factor Expression in the Neonatal Rat Kidney / 대한신장학회잡지

The renin-angiotensin system plays an important role in renal growth and development. Exposure of the fetus or neonate to angiotensin converting enzyme (ACE) inhibitors increases mortality, growth retardation, and results in renal anomalies. This study was designed to investigate the effects of ACE inhibition in the neonatal rat on the expression of genes known to modulate renal cellular proliferation, cell interactions, and extracellular matrix. Newborn rat pups were treated with enalapril (30mg/ kg/day) or vehicle for 14 days, and kidneys were removed for determination of mRNA for transforming growth factor-beta 1 (TGF- B1) and prepro epidermal growth factor (EGF). Enalapril treatment resulted in 40Yo mortality by day 14 as well as reduced body and kidney weight (P<0.05 vs vehicle group). Also enalapril decreased renal TGF-Bl and EGF mRNA expression (P<0.05). These results indicate that ACE inhibition in the developing kidney reduces the renal expression of critical growth factors, which may account for renal growth impairment.