Two different mechanisms of calcium spike modulation by dopamine.
Dopamine (10 to 50 microM) modulates in two different ways the duration of the Ca2+-dependent action potential recorded in the cell body of identified neurons of the snail Helix aspersa. In some neurons (cells E13 and F1) dopamine increases the amplitude of their Ca2+-dependent spike plateau by decreasing the S-current (Klein, M., J.S. Camardo, and E. R. Kandel (1982) Proc. Natl. Acad. Sci. U.S.A. 79: 5713-5717), a K+ current controlled by cyclic AMP. In another neuron (cell D2), dopamine decreases the Ca2+-dependent plateau of the somatic action potential by evoking a decrease in Ca2+-current resulting from a decrease in Ca2+ conductance. Both modulatory effects could be observed in the same single neuron in which dopamine induces decreases of both the Ca2+ conductance and cyclic AMP-dependent K+ conductance. Nevertheless, in these cells (such as cell F5) dopamine only evokes a decrease of the amplitude of the Ca2+ spike plateau. Since the modulation of the duration of the Ca2+ action potential recorded in the neuronal soma has been shown to constitute a good model of events taking place at synaptic endings, it is suggested that these modulatory mechanisms evoked by dopamine may be involved in processes of presynaptic facilitation and inhibition.
D000200:Action Potentials / Q000187:drug effects*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D002118:Calcium / Q000502:physiology*; D004298:Dopamine / Q000494:pharmacology*; D004553:Electric Conductivity; D006372:Helix, Snails; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000502:physiology
D000262:Adenylyl Cyclases; D002118:Calcium; D004298:Dopamine