FIG. 3.
Cardiac expression of ETA and ETB receptors in cre(Tg); ETAflox/flox mice. (a) Real-time RT-PCR on cardiac RNA showed a 78% reduction of the ETA mRNA level and no change in the ETB mRNA level in cre(Tg); ETAflox/flox mice compared to their genetic controls (n = 3 per genotype; #, P < 0.05 for cre(Tg); ETAflox/flox versus each genetic control groups). The β-actin mRNA was used as an internal standard. (b) Radioligand-binding assay for endothelin receptors on cardiac membrane preparations showed no statistically significant change in overall ET-1 binding, twofold higher levels of ETB (P < 0.05), and a trend toward lower levels of ETA (P < 0.07) in the cre(Tg); ETAflox/flox mice compared to the genetic controls [n = 4 for the cre(Tg); ETAflox/flox group; n = 8 for the genetic control group].