Effect of Long-term Angiotensin-converting Enzyme Inhibition on Endothelial Function in Patients with the Insulin-resistance Syndrome

Cardiovascular risk factors such as hypertension, diabetes, and dyslipemia are associated with an impaired endothelium-dependent vasodilation. In patients with type 2 diabetes mellitus, these risk factors are frequently clustered. We investigated whether long-term treatment with the angiotensin-converting enzyme (ACE) inhibitor perindopril can improve endothelium-dependent vasodilation in this particular group of patients. We selected 10 patients with type 2 diabetes and hypertension (age 59.4±3.2 years, body mass-index 29.7±1.5 kg-m -2 , blood pressure 169±6/92±1 mm Hg, total cholesterol 6.6±0.3 mM). Using venous occlusion plethysmography, we recorded the increases in forearm blood flow (FBF) in response to three vasodilator stimuli: (a) 5 min of forearm ischemia, (b) infusion of the endothelium-dependent vasodilator methacholine (Mch) into the brachial artery (0.03, 0.3, and 1.0 μg/min/100 ml), and (c) intraarterial infusion of the endothelium-independent vasodilator sodium nitroprusside (SNP 0.06, 0.2, 0.6 μg/ min/100 ml). This procedure was repeated after 6 months of treatment with perindopril 48 mg/day. Forearm vascular resistance (FVR) was calculated by the quotient of the mean arterial pressure (MAP) and the FBF. Perindopril reduced blood pressure (BP) by 19/10 mm Hg (p< O.OS) and increased baseline FVR, but improved neither the maximal percentage decrease in vascular resistance induced by Mch (from -80±2 to -82±2%) nor that induced by SNP (from -73±3 to -72±3%). Perindopril decreased the FVR reached after the ischemic stimulus from 6.5±1.2 to 4.8±0.6 U (p<0.05). Six months of treatment with perindopril improved neither the endothelium-dependent nor endothelium-independent vasodilation, but significantly reduced minimal FVR (p< 0.05). These observations suggest a reduction of structural vascular changes after long-term ACE inhibition