Visualization and quantitative analysis of leukocyte dynamics in retinal microcirculation of rats.
OBJECTIVE
Recent studies have demonstrated that leukocytes play an important role in microcirculatory flow disturbances. A few methods are available to investigate leukocyte dynamics in retinal microcirculation. The authors explored leukocyte dynamics in the retina of rats with acridine orange digital fluorography.


METHODS
Acridine orange digital fluorography produces high-resolution images from a scanning laser ophthalmoscope with the use of a fluorescent nuclear dye of acridine orange, which has been used for staining nucleic acids of cells in histochemical and cytochemical studies. The images were recorded on S-VHS tapes and were investigated with a personal computer-based image analysis system.


RESULTS
Fluorescent leukocytes in the retinal microcirculation were visualized. Highly magnified images could be obtained because of the high dioptric power of the rat eye compared with the primate eye. It was possible to observe leukocyte deformation in narrow capillaries and nuclei of vascular endothelium. At arteriolar bifurcations, leukocytes moved preferentially into the branch with the higher flow rate. "Preferential channels" were identified in which predominantly leukocytes were delivered; the channels were characterized by high flow velocity and a straight, short capillary route. The average leukocyte velocities of the arteries, veins, and capillaries are 29.5 +/- 7.3, 17.4 +/- 5.3, and 1.4 +/- 0.4 mm/second, respectively.


CONCLUSIONS
This study demonstrates that microcirculatory dynamics of leukocytes can be visualized and analyzed quantitatively in rats in vivo with acridine orange fluorography. This method may be a promising tool to reveal how leukocytes contribute to retinal flow disturbances under various pathologic conditions.
Nishiwaki
H
H
Department of Ophthalmology, Faculty of Medicine, Kyoto University, Japan.
Ogura
Y
Y
Kimura
H
H
Kiryu
J
J
Miyamoto
K
K
Matsuda
N
N
D000165:Acridine Orange / Q000008:administration & dosage; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D002465:Cell Movement; D005451:Fluorescein Angiography / Q000379:methods; D005456:Fluorescent Dyes / Q000008:administration & dosage; D007091:Image Processing, Computer-Assisted; D007958:Leukocyte Count; D007962:Leukocytes / Q000502:physiology*; D008833:Microcirculation / Q000502:physiology; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods; D051381:Rats; D012161:Retinal Artery / Q000502:physiology; D012171:Retinal Vessels / Q000502:physiology*; D012212:Rheology
D005456:Fluorescent Dyes; D000165:Acridine Orange