Transmitter regulation of plateau properties in turtle motoneurons.
In motoneurons, generation of plateau potentials is promoted by modulators that block potassium channels. In voltage-clamp experiments with triangular voltage ramp commands, we show that cis-(+/-)-1-aminocyclopentane-1, 3-dicarboxylic acid (cis-ACPD) and muscarine promote the generation of plateau potentials by increasing the dihydropyridine sensitive inward current, by increasing the input resistance, and by depolarizing the resting membrane potential. Type I metabotropic glutamate receptors (mGluR I) mediate the effects of cis-ACPD. Baclofen suppresses generation of plateau potentials by decreasing the dihydropyridine sensitive inward current, by decreasing the input resistance, and by hyperpolarizing the resting membrane potential. These results suggest that membrane properties of motoneurons are continuously modulated by synaptic activity in ways that may have profound effects on synaptic integration and pattern generation.
Svirskis
G
G
Laboratory of Neurophysiology, Biomedical Research Institute, Kaunas Medical Academy, 3000 Kaunas, Lithuania.
Hounsgaard
J
J
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001418:Baclofen / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D020746:Calcium Channels, L-Type; D003515:Cycloleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009116:Muscarine / Q000494:pharmacology*; D009543:Nifedipine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists; D012118:Resorcinols / Q000494:pharmacology; D013116:Spinal Cord / Q000502:physiology*; D019789:Tetraethylammonium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014426:Turtles
D001565:Benzoates; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate; D012118:Resorcinols; C104077:metabotropic glutamate receptor type 1; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; C079694:alpha-methyl-4-carboxyphenylglycine; D013779:Tetrodotoxin; C079215:3,5-dihydroxyphenylglycine; D019789:Tetraethylammonium; D001285:Atropine; D009116:Muscarine; D001418:Baclofen; D009543:Nifedipine; D005998:Glycine