ACE and non-ACE pathways in the renal vascular response to RAS interruption in type 1 diabetes mellitus

ACE and non-ACE pathways in the renal vascular response to RAS interruption in type 1 diabetes mellitus. The enormous contribution of renin-angiotensin system (RAS) interruption with ACE (angiotensin-converting enzyme) inhibitors and angiotensin II receptor blockers (ARB) in the treatment of diabetic nephropathy has led to interest in the factors involved in angiotensin II (Ang II) generation. In normal subjects, RAS interruption using an ARB produced a 50% greater renal plasma flow (RPF) rise than with an ACE inhibitor, suggesting a substantial contribution of non-ACE pathways. Moreover, immunohistochemistry studies in kidneys of overtly proteinuric diabetic subjects showed up-regulation of chymase, an alternative Ang II-generating enzyme. Our aim was to determine the degree to which the non-ACE pathways contribute to RAS activation in type 1 diabetes mellitus (DM). Type 1DM patients (N = 37, 14 M/23 F; age 31 ± 2 years; DM duration 16 ± 1.7 years; HbA1c 7.7.0 ± 0.3%) were studied on a high-salt diet. They received captopril 25mg po one day and candesartan 16mg po the next day. RPF and glomerular filtration rate (GFR) were measured before and up to 4 hours after drug administration. Both captopril and candesartan induced a significant rise in RPF (baseline vs. peak