Neurovascular microcirculatory vasodilation mediated by C-fibers and Transient receptor potential vanilloid-type-1 channels (TRPV 1) is impaired in type 1 diabetes

Microvascular dysfunction may have an early onset in type 1 diabetes (T1D) and can precede major complications. Our objectives were to assess the endothelial-dependent (acetylcholine, ACh; and post-occlusive hyperemia, PORH), non-endothelial-dependent (sodium nitroprusside, SNP) and neurovascular-dependent (local heating, LH and current induced vasodilation, CIV) microcirculatory vasodilation in T1D patients compared with matched control subjects using a laser speckle contrast imager. Seventeen T1D patients - matched with 17 subjects according to age, gender, Body-Mass-Index, and smoking status - underwent macro- and microvascular investigations. The LH early peak assessed the transient receptor potential vanilloid type 1 channels (TRPV1) mediated vasodilation, whereas the plateau assessed the Nitirc-Oxyde (NO) and endothelium-derived hyperpolarizing factor (EDHF) pathways. PORH explored sensory nerves and (EDHF), while CIV assessed sensory nerves (C-fibers) and prostaglandin-mediated vasodilation. Using neurological investigations, we observed that C-fiber and A-delta fiber functions in T1D patients were similar to control subjects. PORH, CIV, LH peak and plateau vasodilations were significantly decreased in T1D patients compared to controls, whereas there was no difference between the two groups for ACh and SNP vasodilations. Neurovascular microcirculatory vasodilations (C-fibers and TRPV 1-mediated vasodilations) are impaired in TD1 patients whereas no abnormalities were found using clinical neurological investigations. Clinicaltrials: No. NCT02538120.