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Aims: Arterial endothelial dysfunction is a key early event in atherogenesis, and occurs in asymptomatic adults with Type 1 diabetes mellitus (DM). As angiotensin converting enzyme (ACE) inhibitors have been reported to reverse microvascular endothelial dysfunction acutely, we assessed the longer term effect of ACE inhibition on large vessel endothelial physiology in a randomized, crossover double-blind controlled clinical trial., Methods: Flow-mediated arterial dilatation (FMD), which is largely due to endothelial release of nitric oxide, was assessed by vascular ultrasound in 20 Type 1 DM subjects with known endothelial dysfunction. These subjects, aged 28+/-5 years, were studied before and after 12 weeks oral therapy with either the ACE inhibitor perindopril 4 mg daily or the diuretic hydrene (triamterene 50 mg with hydrochlorothiazide 25 mg) daily., Results: Although perindopril lowered both systolic and diastolic blood pressure by 2.7/3.2 mmHg, respectively (F3,78 = 4.7, P= 0.006; F3,78 = 3.2, P = 0.03), there was no significant effect of either perindopril or hydrene on FMD (baseline FMD before perindopril 4.6+/-2.5%, after 4.1+/-3.4%, baseline FMD before hydrene 5.4+/-3.6%, after 6.0+/-3.3%; F3,78= 1.9, P=0.1). Glycaemic control deteriorated slightly on hydrene whilst lipid levels, heart rate, resting blood flow and the arterial responses to nitroglycerine, a smooth muscle dilator, were unaffected by the treatment given., Conclusion: ACE inhibitor therapy for 3 months did not improve arterial endothelial function in Type 1 DM subjects.

Mesangium enlargement and glomerular basement membrane thickening are cardinal features of diabetic nephropathy. The reasons for these changes are uncertain but decreased degradation of extracellular matrix may play a role. Mesangium degradation can be modulated by factors intrinsic to the kidney or by factors in the circulation. In this study the capacity of leucocyte proteolytic enzymes to degrade mesangium matrix materials was investigated. Leucocytes were obtained from 57 patients with NIDDM (age 58.3 +/- 8.8 years, duration 9.4 +/- 7.3 years, body mass index (BMI) 30 +/- 6 kg m-2, HbA1c 7.7 +/- 2.0%) and 21 control subjects (age 55.1 +/- 14.6 years, BMI 25 +/- 4 kg m-2). Leucocyte lysates from control and NIDDM subjects with normal AER degraded matrix to the same extent (40.6 +/- 8.2% vs 42.9 +/- 13.5%) while lysates from patients with microalbuminuria and proteinuria were less able to degrade matrix (33.0 +/- 14.2% and 26.1 +/- 12.7%, respectively). There was a significant inverse correlation between matrix degradation and AER (r = -0.49) and multiple regression analysis showed that AER was the most important factor determining degradation rate (R2 = 0.24). Degree of metabolic control, age, and blood pressure were not significant factors. The major enzyme(s) responsible for the matrix degradation was identified as metalloproteinase(s). We conclude that leucocytes from diabetic patients with abnormal albumin excretion have a decreased proteolytic capacity to degrade extracellular matrix. This may play a role in the glomerular basement membrane thickening and mesangium expansion which occurs in diabetic nephropathy.