(A) Cardiomyocytes were exposed to PE (1 h). RNA expression was determined by qPCR or microarrays. Linear regression analysis was performed to compare mRNA expression determined by qPCR (ordinate) compared with microarrays (abscissa) (axes are on a log₂ scale). The regression coefficient (r) is 0.98. Results are means (relative to controls) for n=3 different cardiomyocyte preparations. (B) Cardiomyocytes were unstimulated, or exposed to 2 μM PD184352 or 0.5 mM H₂O₂ for the times indicated. Total extracts were immunoblotted with antibodies against phospho-AMPKα (P-AMPK), total AMPKα (T-AMPK), phospho-ERK1/2 (P-ERKs) or total ERK1/2 (T-ERKs). The experiment was repeated with similar results. (C and D) Cardiomyocytes were exposed to PE in the absence (closed bars) or presence (open bars) of PD184352 for 1 h. RNA expression was determined by qPCR. Data were normalized to GAPDH and then to the controls. Results are means±S.E.M. (n=3). *P<0.001, †P<0.01 and ‡P<0.05 relative to PE alone. (E–H) Cardiomyocytes were exposed to ET-1 or PE (1 h) in the absence (black bars) or presence of PD184352 (white bars) or BI-D1870 (grey bars). Expression of selected mRNAs was measured by qPCR. Results are means±S.E.M. for three (Rgs2 and Olr1) or four (other mRNAs) experiments with different cardiomyocyte preparations. mRNAs are grouped according to relative effects of the inhibitors with each agonist. *P<0.001, †P<0.01 and ‡P<0.05 relative to the respective agonist alone; **P<0.001 and #P<0.05 relative to ET-1.