Objective Several methods have been proposed for the evaluation of endothelial dysfunction in patients with cardiovascular risk factors. Whether the flow-mediated dilation (FMD) in medium size arteries is related to the vasodilating response to different agonists in small resistance arteries has not been adequately evaluated. Aim of the present study was to assess the endothelial dysfunction in subcutaneous small resistance arteries (response to acetylcholine, Ach or bradikinin, BK) and in the brachial artery (FMD) in normotensive subjects (NT), essential hypertensives (EHT), patients with primary aldosteronism (PA) and patients with type2 diabetes (DM). Methods 46 DM (20 F, age 39–77 yrs, 14 NT and 32 HT), 6 EHT (3 F, age 40–66 yrs), 6 PA (4 F, age 40- 57yrs), and 4 NT (2 F, age 16–64 yrs) underwent a biopsy of the subcutaneous fat. Small resistance arteries were mounted on a micromyograph and a concentration-response curve to Ach (from 10⁻⁹ to 10⁻⁵) and to BK (from 10⁻¹⁰ to 10⁻⁶) was performed. In all patients we measured, by a high resolution ultrasound, the brachial artery (BA) diameter at rest, during reactive hyperemia (5 mis of BA occlusion); BA flow velocity was measured by pulsed doppler

Results:

There was a small, although statistically significant, correlation between FMD and the maximal response to BK (r = 0.34, p < 0.05) while no significant correlation was observed between FMD and the maximal response to Ach (r= 0.19, ns) in all patients. A significant correlation was observed between BA dilatation after NTG 40 mcg s.l and the maximal response to NTP (r= 0.30, p = 0.05). Conclusions These results indicate that, although endothelial dysfunction may be observed in both small resistance arteries and medium size arteries, the degree of impairment may differ according to the vascular bed observed, and to the pathophysiology of the disease.