Blood flow rates in small vessels of the hamster cheek pouch.

Abstract

Changes in blood flow rates have been used traditionally as criteria of small blood vessel activity, but methods of estimation have been largely subjective or indirect. Recently developed microcinematographic techniques, however, now provide the basis for direct quantitative determination of blood flow velocity and volume in individual microscopic vessels (1,2). Materials and methods. A modification of the method of Hugues(1) was used in quantitative studies of blood flow in vessels of the cheek pouch of the golden hamster. Animals of 100 to 135 g body weight were anesthetized with 0.2 ml/100 g of sodium pentobarbitol (50 mg/ml). The cheek pouch was prepared for observation and immersed in mammalian Ringer's solution according to the technique of Lutz and Fulton(3). Single vessels, 14 to 80 μ in diameter, were viewed through a monocular microscope equipped with a water immersion objective at a magnification of 500X. A zirconium arc light source was used. A beam-splitter, attached to the body tube, projected the light-masked image of a straight segment of a vessel into a Grass 35 mm recording camera. The image was focused so that the direction of blood flow was at right angles to the direction of film movement. During the usual one-second exposure, with the film moving at a constant speed of 250 mm/sec, streaks formed by individual moving blood cells were superimposed on the film at an angle. The mean angle formed by the blood cells was then determined by taking an average of 5 direct measurements along the 25 cm strip of developed negative. Inside diameters of the vessels were measured before and after each exposure with an optical micrometer. The mean velocity (V) of the blood cells in mm/sec was calculated by the following formula, where β is the mean angle formed by the blood cells, f is the film speed (250 mm/sec), and M, the magnification of the image on the film: The mean blood cell volume flow rate (Q) in mm3/sec was calculated from the formula Q = Vπr2 where r is the vessel radius.