Using μ-PIV to Interrogate the Endothelial Surface Layer in Arterioles in vivo

The existence of a hydrodynamically relevant endothelial surface layer (ESL) is well established in capillaries and venules. Since the ESL on vascular endothelial cells likely has broad implications for endothelial-cell function, it is necessary to determine the extent of its presence in arterioles. We applied microviscometric analysis to data obtained using micro-particle image velocimetry (μ-PIV) in arterioles of wild-type mice. Data acquisition was triggered with the ECG at peak systole. Results reveal an ESL that is ˜0.38 μm in thickness in arterioles (n=18), compared with ˜0.53 μm (n=23) in venules. This difference is significant (p=0.055).