Functional heterogeneity of large and small resistance arteries isolated from biopsies of subcutaneous fat

Few studies using human subcutaneous resistance arteries acknowledge the possibility of functional heterogeneity in these vessels. Large (∼500 μm) and small (≥200 μm) resistance arteries (n=11) and veins (n=5) were identified using physical, structural and functional criteria in 14 biopsies of human gluteal fat. Endothelium-dependent relaxation was not evident in veins, while, unlike small resistance arteries (E_max 95.74±1.86%; −log IC₅₀ 7.28±0.09), large resistance arteries with an intact endothelium failed to respond to acetylcholine. These results suggest that large resistance arteries may lack muscarinic receptors on the endothelium and emphasise the importance of careful vessel selection and characterisation in studies using human resistance arteries.