title: Ionic mechanism underlying muscarinic acetylcholine response in the rabbit sinoatrial node.
abstract: 1. The clusters composed of 10-20 cells of the rabbit sinoatrial node were prepared by coronary perfusion of collagenase and their response to ionophoretic application of ACh was recorded. The hyperpolarizing response showed a sigmoidal onset without any clear latency when the ACh pipette was positioned close to the cell surface. 2. Equations describing the kinetics and amplitude of the ACh-induced K current were determined based on the reported experimental results obtained by relaxation and noise analysis. 3. The kinetics of the ACh-induced K current simulated well the time course of the ACh response and also the effect on the spontaneous action potential when data on the kinetics was incorporated into the S-A node pacemaker mathematical model.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D011817:Rabbits; D011950:Receptors, Cholinergic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D012849:Sinoatrial Node / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
chemical_list: D007473:Ion Channels; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D000109:Acetylcholine