Affiliations: Department of Biomedical Engineering, National Cardiovascular Center Research Institute, Suita, Osaka, Japan | Division of Physiology and Biosignaling, Osaka University Graduate School of Medicine, Suita, Osaka, Japan | Division of Pathogenesis and Control of Oral Disease, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
Note: [] Corresponding author: Dr. Junji Seki, Department of Biomedical Engineering, National Cardiovascular Center Research Institute, 5‐7‐1 Fujishiro‐dai, Suita, Osaka 565‐8565, Japan. Tel.: +81 6 6833 5012 ext 2432; Fax: +81 6 6872 7485; E‐mail: sekij@ri.ncvc.go.jp.
Abstract: In order to clarify the phase relationship between velocity pulse and pressure pulse propagating along microvessels, the red cell velocity and intravascular pressure were simultaneously measured in the rat pial arterioles of 41–53 μm in diameter with a high temporal resolution by a laser‐Doppler anemometer and a servo‐null micropressure system. It was found that the velocity pulse preceded the pressure pulse in all the measured arterioles by 18.7–35.6 ms. The corresponding phase difference was 43.6±6.9° (mean ± SD), which is not statistically different from 45°. The value is consistent with the phase difference predicted for the blood flow in microvessels with a small reflection coefficient at frequencies as low as the heart rate of the rats. The present results suggest that the upstream changes in blood flow are transmitted by the velocity pulse faster than by the pressure pulse in the microvasculature.
