Fig. 5.

Chronic hypoxia upregulates VEGF receptors. Whereas Western blot quantification revealed that VEGF levels were not altered by chronic hypoxia, abundances of VEGF tyrosine kinase receptors were significantly increased by chronic hypoxia. VEGF R1 levels were increased by 107% and VEGF R2 levels were increased by 156% in hypoxic arteries. Receptor levels presented here were measured relative to amounts in a standard pool of normoxic carotid arteries. In light of the fact that both fetal and adult samples were run on the same gel with the same standards, the lanes with the adult samples are shown here adjacent to the previously published standard and fetal bands (1) for all 4 groups. Bar graphs for KDR represent averages of all glycosylated bands, but for Flt-1 only the 250-kDa band was used for quantification because the 230-kDa band was absent in the hypoxic arteries. Results are presented as mean ± SD for n = 6 for all experimental groups. Comparative significant differences: *P < 0.05 via ANOVA.