Association of Somatic and N-domain Angiotensin Converting Enzymes (ACEs) from Wistar rats tissues with renal and pancreatic dysfunctions in Diabetes Mellitus
Ronchi FA; Casarini DE
Department of Medicine, Nephrology Division, UNIFESP, São Paulo, SP, Brazil
Objective: This study sought to examine the association of somatic ACE with 136 kDa (sACE) and N-domain ACE with 69 kDa (nACE) from Wistar rats tissues with renal and pancreatic dysfunction in diabetes mellitus.
Design and Methods: Diabetes mellitus was induced by injection of 50 mg/Kg streptozotocin i.p. Three groups of Wistar rats (n=5, for each group) were used in this study: diabetic treated with insulin (DT) and not treated (DnT) and control (C). We analyzed the arterial blood pressure, glycemia, proteinuria, protein expression by Western Blotting (WB) and the ACE activity of renal and pancreatic homogenate tissues using Hipuryl-His-Leu (HHL) and Z-Phe-His-Leu (ZPhe-HL) as substrates. The ratio ZPhe-HL/HHL higher than 1.0 express the presence of nACE.
Results: Glycemia and proteinuria, was increased in DnT group compared to C and DT groups. The ratio of ZPhe-HL/HHL hydrolysis by ACEs of renal tissue was increased for DnT and DT groups (8.3±0.89 and 6.59±0.39, respectively) compared to C (4.6±1.55). This ratio for the pancreas tissue was decreased for DnT and DT groups (4.86±0.79 and 5.87±1.07, respectively) compared to C (20.0±6.1). WB analysis of pancreas homogenate evidenciated a decrease of sACE and nACE expression for the DT and DnT groups compared to C group. The protein expression of nACE from the renal tissue of DnT group was decreased compared to DT. Conclusion: The pancreas profile demonstrated that the insulin treatment might not protect the tissue alterations. The detection of higher ratio ACE activity in the kidney homogenate of the groups DnT and DT could be associated to the nACE (69 kDa). Renal nACE activity was increased in DnT and DT group compared to C, despite the reduced and enhaced immunostaining intensivity, respectively, emphasizing the important role of tissue nACE in etiology of complications in diabetes. Higher nACE levels as result of activation of renin angiotensin system intra-renal are suficient to initiate the events leading to diabetic nephropathy due to a probable disorder in the sodium captain and inactivation of Ang1-7 a vasodilator peptide. (Supported by the FAPESP)
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