2007 Volume 1 Issue 1 Pages 12-15
We previously reported that the average velocity of RBC in single capillaries in anesthetized rat cerebral cortex measured at 250 frame/s was 1.43±1.03 mm/s under physiological conditions. Since we have noticed that the apparent average velocity tends to be higher when the frame (sampling) rate is increased, we investigated in detail the velocity profile at different frame rates. In anesthetized rats, intravenously injected FITC-labeled RBCs were detected in the intraparenchymal tissue through a cranial window at 125, 250 and 500 frames/s with a high-speed laser-scanning confocal fluorescence microscope. RBC velocity and number of RBCs were automatically calculated with Matlab® domain our own software (KEIO-IS2). The RBC velocity in capillaries was found to be dependent upon frame rate, with average values of 0.85±0.43 mm/s at 125 frames/s, 1.34±0.73 mm/s at 250 frames/s and 2.09±1.81 mm/s at 500 frames/s. The velocity distribution was similar among different rats and most values lay within a relatively small range around 1.0 mm/s at any frame rate examined. We conclude that some RBCs, which flow at high speed, are missed at lower frame rates. [MVRC 1(1): 12-15, 2007]
