Quantitative analysis of leukocyte dynamics in retinal microcirculation of rats with short-term ischemia-reperfusion injury

Abstract

PURPOSE. To characterize the time course of complete recovery of leukocyte velocities in the retinal microcirculation of rats from short-term (5-minute) retinal ischemia. METHODS. After 5 minutes of retinal ischemia produced by clamping the optic nerve, resulting in the occlusion of both central retinal artery and the central retinal vein, we used acridine orange (AO) and a scanning laser ophthalmoscope (SLO) to observe the velocities of leukocytes in precapillary arteriole (v a) , capillary (v c) and postcapillary venule (v v) . Measurements were taken at reperfusion time points of 5, 10, 15, 20, 30, 40, 50, 60 and 80 minutes for the ischemic eyes and at 12, 22, 42 and 62 minutes for the control eyes, respectively. RESULTS. Each control velocity was arteriole 25.1 ± 4.3 mm/ s; venule 16.9 ± 3.2 mm/s; and capillary 1.54 ± 0.31 mm/s, respectively. The leukocyte velocities after 5 minutes of ischemia in arteriole and venule recovered completely within 80 minutes of reperfusion; however, the recovery patterns were different. The recovery pattern showed a biphasic increase in arterioles and a monophasic increase in venules. The velocity in capillaries half recovered rapidly, within 5 minutes of reperfusion, but the subsequent recovery was slower and was not complete even at 80 minutes of reperfusion. CONCLUSIONS. In this study, leukocyte velocities in arterioles, venules and capillaries exhibited different recovery patterns following retinal ischemia and subsequent reperfusion. Capillaries, at least within 80 minutes of reperfusion, may have difficulty recovering completely from even short-term (5-minute) ischemia.