Low concentrations of muscarine potentiate M-current in bullfrog sympathetic B-neurones

• Published in: Journal of the autonomic nervous system Vol. 67; no. 1; pp. 89 - 96
• Main Authors: Kurennyi, Dmitri E, Chen, Hsinyo, Smith, Peter A
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 03.12.1997; Elsevier Science
• Subjects: Acetylcholine; Activation kinetics; Adrenergic Fibers - drug effects; Animals; Biological and medical sciences; Calcium Channels - drug effects; Calcium Channels - metabolism; Cell Membrane - drug effects; Cell Membrane - metabolism; Female; Freshwater; Fundamental and applied biological sciences. Psychology; FURA-2; G-protein; In Vitro Techniques; Intracellular calcium; Male; Membrane Potentials - drug effects; Muscarine - pharmacology; Muscarinic Agonists - pharmacology; Patch-Clamp Techniques; Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ; Potassium channel; Protein kinase; Rana catesbeiana; Receptors, Muscarinic - drug effects; Superior cervical ganglion; Vertebrates: nervous system and sense organs; Intracellular calcium; FURA-2; Protein kinase; Superior cervical ganglion; G-protein; Activation kinetics; Acetylcholine; Potassium channel; Calcium; Amphibia; Electrophysiology; Salientia; Ionic channel; Ionic current; Sympathetic nervous system; Dose activity relation; Muscarine; Vertebrata; Autonomic nervous system; Cervical ganglion; Ranidae; Membrane potential; Potassium; Rana catesbeiana
• ISSN: 0165-1838; 1872-7476
• DOI: 10.1016/S0165-1838(97)00103-3

The concentration-dependence of the effect of muscarine on M-current ( I M) and the underlying M-conductance ( g M) in B-cells of bullfrog sympathetic ganglion was examined using whole-cell recording techniques. High concentrations of muscarine (≥200 nM) produced the classical suppression and over-recovery of steady-state I M at −30 mV. By contrast, low concentrations of muscarine (≤30 nM) shifted the g M activation curve to more negative potentials, increased the activation time constant ( τ a) and increased steady-state I M. This effect may reflect muscarine-induced changes in submembrane Ca 2+ concentration.