Effect of repetitive asphyxia on leukocyte-vessel wall interactions in thedeveloping chick intestine

Background/Purpose: Information on leukocyte-vessel wall interactions (LVWI ) during development of the immature intestine is scarce. The authors desig ned an experimental model for studying the microcirculation in the developi ng intestine of chick fetuses at days 13 (n = 12), 15 (n = 17), and 17 (n = 19) of incubation (0.6, 0.7, and 0.8 of the incubation lime, respectively) using intravital microscopy. Methods: The authors investigated whether episodes of asphyxia increase LVW I and induce tissue damage in the developing intestine. Asphyxia was induce d by clamping of the chorioallantoic vein for 6 periods of 5 minutes each, with 5-minute intervals, whereas in sham groups a sham procedure was perfor med, Video recordings were made before as well as 10, 20, and 30 minutes af ter the end of the asphyxia or sham protocol. Results: Baseline number of rolling leukocytes per minute significantly inc reased (P <.001)from 0 at 0.6 incubation to 1.5 and to 4 at 0.7 and 0.8 inc ubation time, respectively. At 0.6 and 0.7 incubation no adherent leukocyte s were observed under baseline conditions, whereas at 0.8 incubation single leukocytes adhered to the venular wall. LVWI variably inexperiments. creas ed during the course of the experiments. Asphyxia neither enhanced LVWI nor induced histological damage in the intestine. Conclusions: These findings indicate that (1) leukocyte-vessel wall interac tions mature during fetal development, and (2) repetitive episodes of asphy xia induce neither an inflammatory response nor histological tissue injury in the developing intestine from 0.6 to 0.8 incubation. The authors hypothe size that immaturity of leukocyte-vessel wall interactions, as part of the nonspecific host defense to invading bacteria, might play a role in the dev elopment of necrotizing enterocolitis in premature neonates. Copyright (C) 2000 by W.B. Saunders Company.