Effects of intracranial pressure on the pial microcirculation in rats studied by a fiber-optic laser-Doppler anemometer microscope.
The fiber-optic laser-Doppler anemometer microscope (FLDAM) developed in our laboratory was applied to measure red cell velocity in individual pial microvessels in rats to determine the effect of intracranial pressure (ICP) on the pial microcirculation. The red cell velocity and the vessel diameter of pial microvessels were measured through a closed cranial window at controlled values of ICP between 0 and 50 mmHg. As ICP increased from 0 to 50 mmHg, the average relative diameter of venules with respect to the diameter at an ICP of 5 mmHg decreased from 1.18 +/- 0.12 (mean +/- SD) to 0.74 +/- 0.08 and the average relative velocity increased from 0.80 +/- 0.20 to 1.83 +/- 0.42 monotonically. The changes in diameter and velocity of arterioles with ICP were small, and they were not significantly different from those values at an ICP of 5 mmHg except for the diameter at an ICP of 20 mmHg. The mean volume flow rates calculated assuming a circular vessel cross-section did not show any statistically significant change with ICP between 0 and 50 mmHg in both arterioles and venules, which supports the concept of autoregulation.
Seki
J
J
Department of Biomedical Engineering, National Cardiovascular Center Research Institute, Osaka, Japan.
Sasaki
Y
Y
Oyama
T
T
Yamamoto
J
J
D000818:Animals; D001783:Blood Flow Velocity; D001808:Blood Vessels; D004912:Erythrocytes / Q000166:cytology; D005336:Fiber Optic Technology; D007427:Intracranial Pressure / Q000502:physiology*; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008853:Microscopy / Q000379:methods*; D055100:Optical Fibers; D010841:Pia Mater / Q000098:blood supply*; D051381:Rats; D017208:Rats, Wistar