Objectives: The aim of the present study was to assess the forearm blood vasodilatory response to iontophoretically applied of acetylcholine (Ach) (made up to a 2% solution in deionized, sterile water), an endothelium-dependent vasodilator, and to local skin heating at 44°C, an endothelium-independent vasodilator, in obese women : To investigate the endothelial function of the microcirculation.

Methods: Microvascular endothelium-dependent and endothelium-independent vasodilations were evaluated in 45 women (15 lean, 15 overweight and 15 obese : mean age 36 year) with laser Doppler flowmetry coupled with the iontophoresis technique. This pharmacological method consists in the investigation of the induced change in regional blood flow by Doppler effect in response to local infusion of a cumulative concentration of vasoactive substances like acetylcholine on forearm blood (three doses). This approach is currently used alone and appears as the reference method for the non-invasive assessment of endothelial function in human.

Results (%) are expressed as acetylcholine-induced percentage changes in perfusion index versus basal values.

Results: Our primary results indicate that the mean response of forearm blood flow to acetylcholine, was greater in lean normal subjects (1481 % of the baseline) than in obese (139 % of the baseline) and overweight patients (196 % of the baseline).

These results suggest that a significant difference exists in the endothelial function and vascular reactivity between lean, obese and overweight women.

Conclusion: Obesity is also associated with impaired endothelium-dependent vasodilatation which is considered to be an increasingly important risk factor for cardiovascular disease and a primary cause of microvascular dysfunction