Exposure to alternating hypoxia and hyperoxia causes severe proliferative retinopathy in the newborn rat

• Published in: Pediatric research Vol. 36; no. 6; pp. 724 - 731
• Main Authors: PENN, J. S, HENRY, M. M, TOLMAN, B. L
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01.12.1994
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Delivery. Postpartum. Lactation; Disorders; Gynecology. Andrology. Obstetrics; Humans; Infant, Newborn; Medical sciences; Oxygen - adverse effects; Partial Pressure; Rats; Rats, Sprague-Dawley; Retinal Vessels; Retinopathy of Prematurity - etiology; Premature; Animal model; Intensive care; Oxygen; Retinopathy; Rat; Pathogenesis; Rodentia; Proliferation; Oxygenotherapy; Newborn diseases; Eye disease; Vertebrata; Mammalia; Newborn animal; Hyperoxia; Hypoxia; Neovascularization
• ISSN: 0031-3998; 1530-0447
• DOI: 10.1203/00006450-199412000-00007

Exposure to variable hyperoxia has recently been shown to be much more effective at producing proliferative retinopathy in the newborn rat than exposure to constant hyperoxia. To incorporate a more clinically relevant oxygen-exposure paradigm in our studies, we have now used a cycle between 50 and 10% oxygen and have compared its effects with those found using new exposures to the previously used 80/40% cycle. Starting at birth and continuing for 14 d, rats were exposed to environments that cycled between 50 and 10% oxygen or 80 and 40% oxygen every 24 h. After exposure, some rats were killed for assessment of retinal vascular development. Others were removed to room air for 4 d before killing and evaluation for the presence of abnormal neovascularization--a clinical consequence believed to be promoted by termination of oxygen therapy. The 50/10% cycle resulted in greater retardation of retinal blood vessel development during oxygen than that found in the 80/40% exposure group. After 4 d postexposure in room air, the incidence of preretinal neovascularization was 97% in the 50/10% rats and 72% in the 80/40% group. Clearly, the overall amount of oxygen the subject receives is less critical than other parameters of its administration in producing proliferative retinopathy. Also, the range of variation (40% in both cases) is not the controlling characteristic. Our results suggest that consistency of oxygen level and avoidance of hypoxic levels should be important concerns in neonatal oxygen therapy.