Figure 5. K5R expression was down-regulated in the retina of the oxygen-induced retinopathy rat model. Rats were exposed to 75% oxygen from P7 to P12 of age and then returned to room air at P12. Total RNA was isolated from the retina of the OIR rats at P14 and P16. mRNA levels of K5R were quantified with real-time RT–PCR and normalized with 18s RNA levels and expressed as % of that in age-matched normal rats (mean±SD, n=3). Values significantly lower than control are indicated (*p<0.05). K5R mRNA levels were significantly decreased in the retina of the OIR models, compared to that in normal rats.