Evidence for a role of central serotonergic neurones in digitalis-induced cardiac arrhythmias

EVIDENCE indicates that digitalis drugs administered intravenously increase central sympathetic outflow and that this in turn results in cardiac arrhythmias 1–6 . The central nervous system transmitter(s) that mediates this effect is not known. According to Saito et al. , noradrenaline, the primary transmitter studied so far, is not involved in the case of guinea pigs 7 . 5-Hydroxytryptamine (5-HT) however, may be an important chemical mediator regulating central sympathetic outflow 8,9 , and it is involved in the respiratory arrest induced in rats by intravenous administration of digitoxigenin 10 . We now report evidence that suggests that brain 5-HT is involved in digitalis-induced cardiac arrhythmias.