Cardiac repolarization and striatal dopamine transporter function are interrelated

Abstract

In Parkinson's disease, striatal dopamine transporter (DAT) binding and cardiac sympathetic function are disturbed. In addition, heart rate (HR)-corrected cardiac repolarisation time (QTc interval), which is partly under autonomic control, is prolonged. Whether there is physiological coupling between striatal DAT binding and QTc time (QTc-DAT relation) is not known. The purpose of this study is to evaluate QTc-DAT relation in healthy young adults. Thirty-five participants (18 women, age 26.4+/-1.8 years; mean+/-SD) were studied with iodine-123 labelled 2beta-carbomethoxy-3beta-(4-iodophenyl) nortropane single photon emission tomography. Signal-averaged ECG was recorded at rest from each participant. QTc interval was computed with Bazett's correction and with the approach by Karjalainen, getting QTc and QTk intervals, respectively. Mean striatal DAT binding, as (striatum-cerebellum)/cerebellum, was 2.63+/-0.31. Mean HR, QT, QTc and QTk intervals were 66+/-9 bpm, 340+/-25 ms, 354+/-18 ms and 351+/-16 ms, respectively. HR-QT correlation was -0.63, P value of less than 0.001. HR was not related to striatal DAT binding. QTc-DAT and QTk-DAT relations were significant, r = -0.50, P = 0.004 and r = -0.59, P = 0.0002, respectively. In linear regression model, striatal DAT binding explained 35% of the variance of QTk interval (95% confidence interval: -46.9 to -13.0, P = 0.0002). This study suggests significant physiological QTc-DAT relation in young healthy adults. QTc interval measurements might carry diagnostically important information in clinical conditions, which have an effect on both striatal DAT binding and cardiac sympathetic function.