Cyclic adenosine monophosphate (cAMP) levels and adenylyl cyclase (AC) 6 (AC6) expression are unchanged in hypoplastic left heart syndrome (HLHS) compared with the non-failing right ventricle (NF-RV), whereas expression of AC5 is increased in decompensated (D)-HLHS. (A) cAMP levels determined by enzyme-linked immunosorbent assay are unchanged in HLHS (NF-RV, n = 8; compensated [C]-HLHS, n = 7; D-HLHS, n = 8). Messenger RNA levels of (B) AC5 and (C) AC6 were determined by real-time polymerase chain reaction (NF-RV, n = 8; C-HLHS, n = 8; D-HLHS, n = 8). Results are presented as the mean with the standard error (error bars).