Interaction between leukocytes and erythrocytes in the human retina: Effects of pentoxifylline on hyperoxia‐induced vasoconstriction during increased neutrophil counts

Abstract

AbstractPurpose We have previously shown that under states of vasoconstriction an interaction between circulating erythrocytes and leukocytes may play a role in the control of blood flow. In the present study we hypothesized that pentoxifylline may alter this interaction during oxygen‐induced vasoconstriction.Methods 24 healthy male subjects participated in this double masked, randomized, placebo‐controlled 2 way cross over trail. In order to increase white blood cell count (WBC) count, 300 μg of G‐CSF was administered intravenously. Vasoconstriction of retinal vessels was induced by oxygen inhalation. 400mg of pentoxifylline or placebo was infused at two different study days. White blood cell flux was assessed with the blue‐field entoptic technique. Vessel calibers were measured with a dynamic vessel analyzer (DVA) and red blood cell velocity (RBCV) was determined with laser Doppler velocimetry (LDV). Retinal blood flow was calculated based on retinal vessel diameters and RBCV.Results Retinal vessel diameter, RBCV, calculated retinal blood flow and white blood cell flow were not altered by administration of pentoxifylline. Hyperoxia induced a pronounced decrease in retinal blood flow parameters. No difference was observed between groups during oxygen breathing in vessel diameters (p=0.54), RBCV (p=0.34), calculated retinal blood flow (p=0.3) and white blood cell flow (p=0.26).Conclusion Our data indicate that short time administration of pentoxifylline does not alter the oxygen‐induced effect on ocular blood flow parameters during leukocytosis.