MODULATION OF DROSOPHILA HEARTBEAT BY NEUROTRANSMITTERS

The heart of Drosophila melanogaster is a simple muscular tube with a posterior pulsatile portion and a thoracic-cranial vessel. The pacemak er, located caudally, is myogenic. Its rate of firing is modulated by neurotransmitters. Serotonin, octopamine, norepinephrine, dopamine, an d acetylcholine accelerate the heart, in that order of potency. Dihydr oxyphenylalanine, gamma-aminobutyric acid, glutamate, and glycine have no effect. Generally, the regularity of the heartbeat is not adversel y affected by treatment with any of these neurotransmitters. We show h ere that amnesiac, a neurological mutation, and Dihydroxyphenylalanine decarboxylase (temperature sensitive), a mutation that interferes wit h synthesis of dopamine, norepinephrine, and serotonin, result in slow er heart rate and reduced regularity across a normal range of temperat ures for these flies. Dopamine-N-acetyltransferase, which is on the ca tabolic route to dopamine, serotonin, and octopamine, has no effect. h ypoactive C reduces the rate of the heart, but its mechanism of action is unknown.