Raised inspired carbon dioxide alone induces neovascularization similar to rop in the neonatal rat

J. M. Holmes, S. Zhang, D. A. Leske

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2 Scopus citations

Abstract

Purpose. Retinopathy of prematurity (ROP) may develop in infants who never experience hyperoxia and therefore raised pCO3 has been suggested as a risk factor. We investigated the effect of raised inspired CO, alone on retinal vasculature in the neonatal rat. Methods. 150 newborn Sprague-Dawley rats were raised in randomly assigned expanded litters (n=25). Rats were exposed to either room air or continuous high CO: (10.0% CO; ±0.1% SD, 21% O2 ±0.4%) for 7 days. Following an additional 5 days in room air, all rats were sacrificed after intracardiac injection of fluorescein under deep anesthesia. The retinas were dissected and flat mounted for ADPase staining and fluorescent microscopy. The presence and number of clock hours of abnormal neovascularization were evaluated in a masked manner and the ratios of vascularized:total retinal area were calculated using computer assisted image analysis. Fishers exact test, ANOVA and Spearman rank correlation were used for analysis, penults. Preretinal neovascularization, at the junction of vascular and avascular retina, occurred in 23% of rats exposed to high CO2 vs 0% exposed to room air (p<0.001). The severity of neovascularization in the high CO; rats ranged from 0 to 6 clock hours. Rats raised in high CO2 demonstrated growth retardation (day 7 weight 9.1 g + 1.7g vs 10.5g± 1.5g, p=0.001). The ratio ofvascularized:total retinal area was smaller in rats exposed to high CO2 (93% + 4% vs 95% + 2%, p=0.006), and the severity of neovascularization was inversely correlated to this ratio (r= -0,51, p<0.001 ) Conclusions. Elevated inspired CO; alone, followed by room air recovery, was associated with abnormal neovascularization in the neonatal rat. This further suDoorts an indeoendent role for raised oCO, in the develooment of ROP.

Original languageEnglish (US)
Pages (from-to)S611
JournalInvestigative Ophthalmology and Visual Science
Volume38
Issue number4
StatePublished - 1997

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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