Role of Brain Angiotensin-II in Development of Experimental Diabetic Nephropathy in Wistar Rats

Abstract The renin-angiotensin-aldosterone system (RAAS) plays a key role in diabetic nephropathy (DN). Angiotensin-II secreted during the RAAS pathway increases nephropathy. It stimulates oxidative stress which can quench nitric oxide. Reduced nitric oxide level aggravates Ang-II-induced vasoconstriction. Ang-II has also emerged as a central mediator of the glomerular hemodynamic changes that are associated with renal injury. Deletion of ACE2 is also noted due to increased Ang-II level which leads to the development of DN. We hypothesize that nephropathy caused by Ang-II in the periphery may be controlled by brain RAAS. ACE inhibitors and ARBs may show the renoprotective effect when administered through ICV without crossing the blood-brain barrier. DN was observed after 8 weeks of diabetes induction through alloxan. Administration of captopril and valsartan once and in combined therapy for 2 weeks, significantly reduced urine output, blood urea nitrogen, total protein in the urine, serum cholesterol, serum creatinine, serum triglycerides, and kidney/body weight ratio as compared to diabetic control rats. Further, combination therapy significantly increased the body weight and serum nitrate level as compared to diabetic control animals. However, increased ACE2 levels in the brain may reduce the sympathetic outflow and might have decreased the peripheral activity of Ang-II which shows beneficial effects in DN.

Angiotensina-(1-9) disminuye el remodelamiento cardiovascular hipertensivo independiente de los niveles de ECA y de angiotensina II / Angiotensin-(1-) reduces hypertensive cardiovascular remodeling independent of ACE and Ang II levels

Resumen: La enzima convertidora de angiotensina I (ECA2) a través de Angiotensina (Ang)-(1-9) más que Ang-(1-7) contrarresta los efectos deletéreos de ECA y Ang II. Se desconoce si Ang-(1-9) es efectiva en el tratamiento del remodelamiento cardiovascular (RMCV) hipertensivo, en ratas con polimorfismo del gen de la ECA. Objetivo: Determinar el efecto de Ang-(1-9) en el tratamiento del RMCV hipertensivo en ratas con niveles genéticamente determinados de ECA y Ang II. Métodos: Ratas normotensas homocigotas, Lewis (LL) y Brown Norway (BN), se les indujo HTA a través del modelo Goldblatt (GB, 2 riñones-1 pinzado). Después de 4 semanas, las ratas hipertensas se rando-mizaron para recibir Ang-(1-9) (602 ng/Kg min) o una coadministración de Ang-(1-9)+A779 (100 ng/Kg min, antagonista del receptor MAS de Ang-(1-7)) durante 14 días mediante una minibomba. Como controles se usaron ratas sometidas a operación ficticia (Sham). Se determinó masa corporal (MC), presión arterial sistólica (PAS), masa ventricular (MV), área de cardiomiocitos (AC), área y grosor de la túnica media (ATM, GTM), fracción volumétrica de colágeno total (FVCT) en el ventrículo izquierdo (VI), niveles proteicos de colágeno tipo I (Col I) en la aorta (Ao) y la infiltración de macrófagos en Ao y VI, por medio de su molécula especifica ED1 (ED1-Ao, ED1-VI). Resultados: La administración de Ang-(1-9) disminuyó significativamente PAS, MV, AC, FVCT, Col I, ATM, GTM, ED1-Ao (-) y ED1-VI, en las ratas hipertensas LL y BN respecto a las ratas GB sin tratamiento, respectivamente. Este efecto no fue inhibido por el antagonista A779. El polimorfismo de la ECA no modificó la respuesta al tratamiento. Conclusión: Ang-(1-9) redujo eficazmente la HTA y el RMCV secundario, independiente al polimorfismo en el gen de la ECA. Este efecto posiblemente es directo ya que no fue mediado por Ang-(1-7). Fondecyt 1100874.

Background: The angiotensin I converting enzyme 2 (ACE2) counteracts the deleterious effects of ACE and Ang II through angiotensin (Ang) -(1-9) rather than Ang-(1-7). In addition, it is not clear whether Ang-(1-9) is effective in the reversal of hypertensive cardiovascular remodeling (CVRM) in rats with ACE gene polymorphism. Objective: To determine the effect of Ang-(1-9) in the prevention of hypertensive CVRM in rats with genetically determined levels of ACE and Ang II. Methods: In normotensive homozygous Lewis (LL) and Brown Norway (BN) rats hypertension was induced by the Goldblatt 2 kidney-1 pinch model. After 4 weeks, rats were randomized to receive Ang- (1-9) (602 ng / Kg min) or the co administration of Ang- (19) + A779 (100 ng / kg min, a MAS receptor antagonist of Ang- (1-7)) for 14 days. Sham operated rats were used as controls. We determined body mass (BM), systolic blood pressure (SBP), ventricular mass (VM), cardiomyocyte area (CA), area and thickness of the aortic media (ATM, TTM), LV total collagen volume fraction (FVCT), type I collagen protein levels (Col I) in the aorta (Ao) and macrophage infiltration in LV and Ao, through its specific molecule ED1 (ED1-Ao, ED1-VI). Results: Continuous administration of Ang- (1-9) significantly decreased SBP, VM, CA, TCVF, Col I, TTM, and ED1 in the aorta and left ventricle of hypertensive rats. This effect was not inhibited by the antagonist A779. ACE polymorphism did not modify the response to treatment. Conclusion: Ang- (1-9) effectively reduced hypertension induced CVRM independent of ACE gene polymorphism. This effect was not mediated by Ang- (1-7).

La sobreexpresión del gen de enzima convertidora de angiotensina homóloga (ECA2) revierte la hipertensión arterial y el remodelado cardíaco experimental / Over expression of the homologous angiotensin converting enzyme (ACE2) gene reverts experimental hypertensión and cardiac remodeling

Antecedentes: La sobreexpresion génica de la enzima convertidora de angiotensina I homologa (ECA2) se asocia con prevención de la hipertrofia y fibrosis cardiaca dependiente de angiotensina (Ang) II. Sin embargo se desconoce si su sobreexpresion reduce la hipertensión arterial (HTA) y revierte el consecuente remodelado miocárdico (RM) dependiente de Ang II. Objetivo: Determinar si la sobreexpresion adenoviral (Ad) del gen de la ECA2 en el miocardio disminuye la HTA y RM experimental en ratas con niveles genéticamente determinados de ECA y Ang II. Métodos: Ratas homocigotas normotensas Lewis (LL) y Brown Borway (BN), con menores y mayores niveles circulantes de ECA y Ang II, respectivamente, se hicieron hipertensas por el procedimiento Goldblatt (GB). Como controles se usaron ratas seudo-operadas (sham). A la semana 5 post cirugía y con HTA establecida > 140 mmHg, las ratas se randomizaron a inyección intramiocárdica con un AdECA2 o Ad proteína fluorescente verde (GFP) como controles de infección. A la semana post infección adenoviral, los ratas se sacrificaron y se determinaron peso corporal (PC, g), masa cardiaca (MC, mg), presión arterial sistólica (RAS, mmHg), área (AC, um2) y perímetro (PERC, um) de cardiomiocitos y contenido de colágeno ( por ciento) miocárdico (CM), sub-endocárdico (CS)ytotal(CT). Resultados: La HTA aumentó significativamente la MC, MCR, AC, PERC como también el CM, CS y CT en las ratas GB vs Sham, sin diferencias en el PC ni por efecto del polimorfismo de la ECA. La sobreexpresion de ECA2 disminuyó significativamente la RAS (15 por ciento y 27 por ciento), AC (25 por ciento y 25 por ciento ) y PERC (17 por ciento y 18 por ciento) en las ratas LL y BN vs ratas hipertensas, respectivamente. Estos resultados se asociaron a una disminución significativa del CS (LL = 37 por ciento, BN = 39 por ciento), CM (LL = 54 por ciento) y CT (LL = 42 por ciento, BN = 22 por ciento) respecto a las ratas GB. Conclusión: En ratas con HTA...

Objective Background. Over expression of the gene for homologous angiotensin I converting enzyme (ACE) is associated with prevention of angiotensin II dependent cardiac hypertrophy and fibrosis. Whether this over expression is able to reduce hypertension and revert cardiac remodeling is unknown. Aim: To determine whether adenoviral ACE2 gene over expression in the myocardium decreases experimental hypertension and cardiac remodeling in rats with genetically determined levels of ACE and ANGII. Methods: Homozygous normotensive Lewis (LL) and Brown Norway (BN) rats with decreased or increased levéis of ACE and Ang II, respectively, were made hy-pertensive using the Goldblatt procedure. Sham opera-ted rats were used as control s. 5 weeks after surgery, when systolic blood pressure reached > 140 mmHg, rats were randomized to receive intramyocardial injec-tion of either AdACE2 or green fluorescent Ad protein (GFP) as infection controlling agents. One week after adenoviral infection, rats were sacrificed. Body weight (BW, Gr), relative cardiac mass (RCM, mG), systolic blood pressure (SBP, mmHg), cardiomyocite área (MA um2) and perimeter (MPER, uM), and myocardial co-llagen content, both subendocardial (SC, percent) and total (TC percent) were measured. Results: Hypertension was associated to significant in-creases in total and RCM, MA, MPER as well as SC and TC in Goldblatt vs normal rats. This was independent of BW and not affected by ACE polymorphism. ACE II over expression significantly decreased SBP (27 vs 15 percent), MA (25 vs 25 percent) and MPER (18 vs 17 percent) hy-pertensive vs normal rats, respectively. Conclusion: Over expression of ACE2 decreased hypertension, hypertrophy and fibrosis in rats with experimental hypertension and different levels of ACE and Ang II. (Fondecyt 1070662).

Effect of chronic oral administration of a low dose of captopril on sodium appetite of hypothyroid rats: Influence of aldosterone treatment

Rats rendered hypothyroid by treatment with methimazole develop an exaggerated sodium appetite. We investigated here the capacity of hypothyroid rats (N = 12 for each group) to respond to a low dose of captopril added to the ration, a paradigm which induces an increase in angiotensin II synthesis in cerebral areas that regulate sodium appetite by increasing the availability of circulating angiotensin I. In addition, we determined the influence of aldosterone in hypothyroid rats during the expression of spontaneous sodium appetite and after captopril treatment. Captopril significantly increased (P<0.05) the daily intake of 1.8 percent NaCl (in ml/100 g body weight) in hypothyroid rats after 36 days of methimazole administration (day 36: 9.2 + or - 0.7 vs day 32: 2.8 + or - 0.6 ml, on the 4th day after captopril treatment). After the discontinuation of captopril treatment, daily 1.8 percent NaCl intake reached values ranging from 10.0 + or - 0.9 to 13.9 ± 1.0 ml, 48 to 60 days after treatment with methimazole. Aldosterone treatment significantly reduced (P<0.05) saline intake before (7.3 + or - 1.6 vs day 0, 14.4 + or - 1.3 ml) and after captopril treatment. Our results demonstrate that, although hypothyroid rats develop a deficiency in the production of all components of the renin-angiotensin-aldosterone system, their capacity to synthesize angiotensin II at the cerebral level is preserved. The partial reversal of daily 1.8 percent NaCl intake during aldosterone treatment suggests that sodium retention reduces both spontaneous and captopril-induced salt appetite

Eritrocitos post trasplante renal y su tratamiento farmacológico: inhibidores de la enzima convertidora de angiotensina versus bloqueadores de los receptores de angiotensina en un caso / Treatment of post kidney transplantation erythrocytosis with angiotensin converting enzyme inhibitors or angiotensin receptor blockers: report of 1 case

A 35 years old male is presented. Eight months after receiving a renal allograft his hypertension worsened and his packed red cell volume raised to 53.7 percent. Enalapril was started and a 500 ml phlebotomy was performed. In three occasions packed red cell volumes decreased excessively and enalapril was discontinued. Finally, the drug was replaced with losartan, normalizing blood pressure values and stabilizing packed red cell volumes. This case illustrates the different reductions in packed red cell volumes induced by enalapril and losartan. These differences could have a therapeutic relevance