Figure 2.

Relative expression of mRNA for P2Y₂ receptors, P2Y₆ receptors and the ratio P2Y₆/P2Y₂ in endothelial cell-denuded aortae of young (A) and old (B) apoE^–/– mice on regular chow. Young apoE^–/– mice (4 months) that had not developed atherosclerotic plaques yet, showed no regional differences in the expression of P2Y₂ or P2Y₆ receptors between aortic arch (AA) and thoracic aorta (TA). In contrast, old apoE^–/– (18 months) with established plaques in the aortic arch had more P2Y₆ receptor transcripts in the atherosclerotic region. β-Actin was used as an endogenous reference gene and the mean value of the TA was used as calibrator and set to one. Results show mean and SEM, n= 5. *P < 0.05, **P < 0.01.