Résumé
By means of flowmotion analysis, it is mainly accepted that, in normal conditions, insulin specifically increases the activity of microvascular smooth muscle. The objective of this study was to compare this effect in severely obese and normal-weight adolescents. Laser Doppler measurements were used to assess cutaneous blood flux (CBF) and flowmotion in response to transdermal iontophoresis of insulin in 20 severely obese adolescents (SOA) aged 12–17 years (BMI = 33.34 ± 1.07 kg/m2), and 16 normal-weight adolescents (BMI = 18.85 ± 0.50 kg/m2). Fasting insulin levels were higher in SOA than in normal-weight adolescents (6.25 ± 1.03 vs. 3.11 ± 0.28 μU/ml, P = 0.007). Net insulin-induced increase of CBF did not significantly differ between SOA and normal-weight adolescents (422.41 ± 146.09 vs. 232.36 ± 80.98 %, P = 0.265). A significant impairment of myogenic flowmotion was detected in SOA compared to normal-weight adolescents in response to insulin delivery (5.91 ± 0.35 vs. 8.12 ± 0.63 %, P = 0.003). Severely obese adolescents exhibit decreased myogenic activity in response to insulin, which may be an early step in the development of insulin resistance.