HTR2A and hydrops fetalis: As previously described in HF and hypertrophy [1], [13], the 5-HT2A-mediated inotropic response in neonatal rat ventricle was not associated with a lusitropic response (Figure 5 bottom right panel), consistent with a non-cAMP-dependent mechanism, probably dependent on myosin light chain phosphorylation as demonstrated in HF [13].