Up-regulation of ETB receptor subtype mRNA by angiotensin II in rat cardiomyocytes.

The effect of angiotensin (ANG) II on the expression of endothelin (ET) receptor subtype (ETA, ETB) mRNA in cultured neonatal rat cardiomyocytes was studied. ANG II (10(-7) M) increased steady-state mRNA levels of ETB receptor, but not ETA receptor, during 6-12 hr incubation, whose effect was dose-dependent (10(-9)-10(-7) M). ANG II receptor type-1 (AT1) antagonist (CV-11974) completely inhibited the ANG II-induced up-regulation of ETB receptor, whereas the inhibitory effect by ANG II receptor type-2 (AT2) antagonist (PD 123319) was incomplete. These results suggest that ANG II up-regulates cardiac ETB receptor, predominantly via AT1 receptor.