The cardiac sympathetic co-transmitter neuropeptide-Y is pro-arrhythmic in human cardiomyocytes by lengthening activation-recovery interval

Abstract Background Myocardial infarction (MI) is associated with sympathetic overactivity, during which the co-release of neuropeptide-Y (NPY) is prominent. NPY is associated with arrhythmia risk and mortality following ST-elevation MI, although the exact mechanisms for this in human cardiomyocytes remains unclear. Purpose We therefore tested the hypothesis that NPY signalling would alter the electrophysiology of human induced-pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) in a way that would promote arrhythmia, and that in patients being treated for MI, high NPY concentrations previously associated with ventricular arrhythmia (>27.3 pg.mL-1) would be associated with comparable ECG changes. Methods Immunohistochemistry and western blot were performed on hiPSC-CMs and ventricular biopsies from human patients undergoing valve surgery. The FRET-based sensor Epac-SH187 was expressed in hiPSC-CMs to monitor the cyclic adenosine 3’,5’-monophosphate (cAMP) response to NPY. A micro-electrode array was used to investigate the effects of NPY on a confluent layer of iPSC-CMs, measuring changes in activation, recovery, conduction velocity and spontaneous automaticity. Additionally, patients presenting with ST-elevation MI had peripheral venous [NPY] measured and compared to 12-lead ECGs recorded following stenting. Results hiPSC-CMs expressed Y1 and Y5 receptor mRNA and protein, which are also expressed in ventricular biopsies from human patients. NPY (1-100 nM) significantly reduced intracellular cAMP levels (n=65), most effectively prevented by Y5 receptor inhibition (1µM CGP71683A, n=40). In a confluent layer of hiPSC-CM, NPY (100 nM) slowed late-repolarisation represented by T-wave peak-end duration (p=0.04), which could be prevented by Y1-receptor inhibition (1 μM BIBO 3304, n=6), and caused prolongation of rate corrected activation-recovery interval (ARIc) (p=0.009, n=6) which could be abolished by Y5-receptor inhibition (n=7). NPY significantly increased automaticity to more than one site of initiation in 4/6 (66.7%) compared to 2/14 (14.3%) control plates (p=0.037), despite no change in conduction velocity. Moreover, in 65 patients being treated for ST elevation MI, those with high peripheral venous NPY concentrations were well matched in terms of cardiovascular risk factors, medications on admission, and pain to balloon times, but had significantly longer corrected QT interval (QTc) on the 12 lead ECG (p=0.04) despite no differences in PR interval, heart rate or electrolyte concentrations. Conclusions NPY slowed late repolarisation and caused ARIc prolongation, which was associated with increased automaticity in human iPSC-CMs. NPY also correlated with QTc-prolongation in patients being treated for MI and may contribute to the increased incidence of ventricular arrhythmia observed in these patients. Antagonists of Y1 and Y5 receptors may therefore offer an adjunct to β-blockade therapy to reduce the risk of ventricular arrhythmia.