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Whether amphetamine acts principally at the plasma membrane or at synaptic vesicles is controversial. We find that d-amphetamine injection into the Planorbis giant dopamine neuron causes robust dopamine release, demonstrating that specific amphetamine uptake is not required. Arguing for action at vesicles, whole-cell capillary electrophoresis of single(More)
It has been well established that the volume of secretory vesicles can be modulated. However, we present the first data demonstrating that the amount of transmitter in a vesicle can regulate its volume. Amperometry and transmission electron microscopy have been used to determine that l-3,4-dihydroxyphenylalanine and reserpine increase and decrease,(More)
Catecholamine release from rat pheochromocytoma (PC12) cells has been observed at zeptomole levels using dc-amperometric detection with carbon fiber microelectrodes. Time-resolved individual exocytic events from PC12 cells have been recorded and analyzed with 1.2 ms time resolution. The average area under 1912 current transients from 13 PC12 cells(More)
Amperometric detection of exocytosis at single chromaffin cells has shown that the distribution of spike areas, or quantal size, is dependent on the volume and catecholamine concentration of individual secretory vesicles. The present work offers an alternate, simplified model to analyze the current spikes due to single exocytotic events. When the cube root(More)
Differential depletion of neurotransmitter by amphetamine in two classes of vesicles, termed large vesicles and small vesicles, has been studied with amperometry. Carbon fiber microelectrodes have been used to monitor and quantify exocytotic events. Current transients, corresponding to individual exocytotic events, have been obtained from the cell body of(More)
We have discovered a neuronal system that releases neurotransmitter via exocytosis from the cell body. In the large dopamine cell of the pond snail Planorbis corneus, depolarization induces rhythmic release of dopamine from the cell body. When a stimulant is applied extracellularly or intracellularly in situ to the cell body, transient dopamine(More)
Carbon-fiber voltammetric electrodes have been used to measure the release of dopamine in the caudate nucleus of an anesthetized rat. Release is induced by electrical stimulation of the medial forebrain bundle. The amplitude of the observed release is attenuated by i.p. injection of amphetamine. A similar attenuation is induced by reserpine; however, at a(More)
Microvoltammetric electrodes were used to monitor dopamine released in the caudate nucleus of the rat after electrical stimulation of the medial forebrain bundle. The time resolution of the technique is sufficient to determine in vivo concentration changes on a time scale of seconds. Direct evidence identifying the substance released as dopamine was(More)
To compare the time course of different mechanisms of chemically stimulated release, amperometric detection of dopamine was carried out at single PC12 cells. The rapid response of carbon fiber microelectrodes allowed the detection of single exocytotic events, thus providing time-resolved information about the dynamics of stimulated release, in particular(More)