Blood Flow Velocity in the Pial Arteries of Cats, with Particular Reference to the Vessel Diameter

Abstract

The blood flow velocity and diameter of feline pial arteries, ranging in diameter from 20 to 200 microns, were measured simultaneously using a newly developed video camera method under steady-state conditions for all other parameters. There was a linear relationship between blood flow velocity and pial artery diameter (y = 0.340x + 0.309), the correlation coefficient being 0.785 (p less than 0.001). The average values for blood flow velocity in pial arteries less than 50 microns, greater than or equal to 50 but less than 100 microns, greater than or equal to 100 but less than 150 microns, and greater than or equal to 150 microns in diameter were 12.9 +/- 1.3, 24.6 +/- 3.4, 42.1 +/- 4.7, and 59.9 +/- 5.3 mm/s, respectively. Blood flow rate was calculated as a product of the cross-sectional area and the flow velocity. The blood flow rate increased exponentially as the pial artery diameter increased (y = 2.71 X 10(-4) x2.98). The average values for blood flow rate in pial arteries less than 50 microns, greater than or equal to 50 but less than 100 microns, greater than or equal to 100 but less than 150 microns and greater than or equal to 150 microns in diameter were 12.8 +/- 1.5, 122.1 +/- 24.8, 510.2 +/- 74.8, and 1524.2 +/- 174.4 10(-3) mm3/s, respectively. Hemorheological parameters such as the wall shear rate and Reynolds' number were also calculated. The data obtained provide a useful basis for further investigations in the field of cerebral circulation.

Vascular dimensions of the cerebral arteries follow the principle of minimum work.

“…19 Moreover, studies in vivo with animal models demonstrated that the blood flow in arteries is approximately proportional to the cube of the diameter of the vessel, e.g., in the canine carotid artery (including progressive remodeling after establishment of an arteriovenous fistula),20 the microvasculature of the rat cremaster muscle,21 and the feline pial arteries. 22 However, the fact that data on branch angles were disappointingly found to scatter considerably around the theoretical optimum, as verified also in the present study, has hindered a general acceptance of the principle of minimum work. The parametric optimization of branch angles has otherwise proved to be irrelevant in terms of functional optimization.…”

Constriction and dysfunction of pial arterioles after regional hemorrhage in the subarachnoid space

“…Of course, resistance is inversely related to the 4th power of the diameter of the vessel (Kobari et al, 1984). Thus, small reductions in the diameter of arterioles can induce significant increases in resistance and ultimately could result in a dramatic decrease in CBF.…”

Blood Flow in Single Surface Arterioles and Venules on the Mouse Somatosensory Cortex Measured with Videomicroscopy, Fluorescent Dextrans, Nonoccluding Fluorescent Beads, and Computer-Assisted Image Analysis

“…Ma et al (1974) used correlated dual slit photometry to measure mean velocities of RBCs in rat cerebral arterioles; after division by a correction factor 1.6 (Baker and Wayland, 1974), their values for mean center velocity for arterioles of different sizes are as follows: 6.8 fLm, 5.8 mm/s; 13.7 fLm, 8.6 mm/s; 23.5 fLm, 13.8 mm/s; and 49 fLm, 26.3 mm/s. Kobari et al (1984) used delay of a sa line bolus at two points to estimate velocities in cat cerebral arterioles; values from their regression line for mean velocities are 20 fLm, 7.1 mmls (V max of 21 mm/s); 50 fLm, 17.3 mm/s; and 100 fLm, 34.3 mm/s. Rosenblum (1969) measured twofold changes in ve locities of marginal red blood cells in mouse pial arterioles during the cardiac cycle.…”