ADRB2 and hydrops fetalis: In order to investigate the mechanisms causing β1-AR non-desensitization, we studied the beating frequency of the neonatal rat cardiomyocytes (NRCMs) under different conditions (an injection of isoprenaline (ISO) for one group and β1-AA for the other) and established three dynamic models in order to best describe the true relationships shown in medical experiments; one model used a control group of healthy rats; then in HF rats one focused on conformation changes in β1-AR; the other examined interaction between β1-AR and β2-adrenergic receptors (β2-AR).