Spectrum analysis of fluctuations of RBC velocity in microvessels by using microscopic laser Doppler velocimetry

The velocity of red blood cells (RBCs) in microvessels of rat mesentery was measured using microscopic laser Doppler velocimetry. In order to estimate the periodicity of the RBC velocity fluctuation accurately, the power spectrum of the velocity was calculated by means of the fast Fourier transform. The amplitude of the pulsatile component was quite large in the spectrum of the RBC velocity fluctuation in arterioles. On the other hand, RBC velocity in venule intermingled the different frequency components. The velocity of the phase shift of the pulsatile component of RBC velocity was estimated by using the cross-spectrum analysis. The propagational velocity of the RBC velocity profiles in arterioles was slower than that of the pulse wave in larger vessels