Spontaneous muscarinic suppression of the Ca-activated K-current in bullfrog sympathetic neurons.
Neurons in bullfrog sympathetic ganglia were voltage-clamped using a single microelectrode. A prolonged outward current which was identified as the Ca-activated K-current secondary to a transient Ca entry through voltage-operated channels was shortened by oxotremorine. An inward Ca-current was not significantly depressed by oxotremorine. It was suggested that muscarinic agonists accelerate the re-closure of K-channels either directly or secondarily via their effects on an intracellular sequestration process of Ca ions. It was also suggested that a small amount of acetylcholine only sufficient to cause a miniature synaptic current via nicotinic receptors could shorten the Ca-activated K-current via muscarinic receptors.
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D000818:Animals; D002118:Calcium / Q000502:physiology*; D002463:Cell Membrane Permeability; D005728:Ganglia, Sympathetic / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D010095:Oxotremorine / Q000494:pharmacology; D011188:Potassium / Q000502:physiology*; D011892:Rana catesbeiana; D011976:Receptors, Muscarinic / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology
D007473:Ion Channels; D011976:Receptors, Muscarinic; D010095:Oxotremorine; D012601:Scopolamine; D011188:Potassium; D002118:Calcium