Blood flow oscillatory patterns in single vessels of rat pial microcirculation evaluated by laser speckle imaging

The present study was aimed to assess blood flow oscillatory patterns in rat pial microcirculation by laser speckle imaging. Laser speckle methods provides maps of cerebral blood flow with elevated temporal and spatial resolution. The study was carried out on male Wistar rats. An open cranial window was prepared on the parietal region. Pial arterioles were classified by Strahler method in five orders by fluorescence microscopy. The blood flow oscillatory patterns were determined by laser speckle imaging in single pial vessels. Power spectrum analysis was performed by wavelet methods under baseline conditions. Arterioles and venules were characterized by blood flow oscillations with frequency components in the ranges 0.005-0.0095 Hz, 0.0095-0.02 Hz, 0.02-0.15 Hz, 0.15-0.5 Hz. Arterioles showed oscillations with higher total power and higher spectral density in the range 0.02-0.15 when compared with venules. Laser speckle imaging allowed us to evaluate arteriolar and venular blood flow oscillations.