The effects of amphetamine on neuromuscular transmission in the lobster.
In vitro electrophysiological techniques were used on an excitatory neuromuscular junction of a walking-limb stretcher muscle of the lobster in order to define the pharmacology of amphetamine on a glutamatergic synapse. A single electrical stimulus in the presence of the drug produced a train of action potentials in the axon innervating the neuromuscular junction, resulting in a staircase-like enhancement of the evoked excitatory junction potential; both effects were antagonized by relatively small doses of haloperidol. In contrast, amphetamine reduced the amplitude of the spontaneous miniature junctional potential, suggesting a postsynaptic site of action; this depressant response to the drug was not antagonized by haloperidol. The data demonstrate that amphetamine concomitantly produces both excitation and depression at a single synapse.
Turkanis
S A
SA
Department of Pharmacology, University of Utah School of Medicine, Salt Lake City 84132.
Partlow
L M
LM
Karler
R
R
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D006220:Haloperidol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008121:Nephropidae; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects*
D000661:Amphetamine; D006220:Haloperidol