These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Characterization of the acetylcholine-induced potassium current in rabbit cardiac Purkinje fibres.
    Author: Carmeliet E, Mubagwa K.
    Journal: J Physiol; 1986 Feb; 371():219-37. PubMed ID: 2422348.
    Abstract:
    Acetylcholine (ACh) induces a K+ current in rabbit cardiac Purkinje fibres. The question was studied whether ACh produces this effect by modifying the properties of K+ channels pre-existing in the absence of the neurotransmitter or whether it induces the formation of a different type of K+ channels. The relaxation properties of the ACh-induced current and its blockade by Cs+ and Ba2+ have been investigated using voltage clamp. During hyperpolarizing or depolarizing voltage pulses of moderate amplitude, the ACh-induced current is time independent. For large voltage pulses, time-dependent changes of the ACh-induced current are observed. These latter changes can be explained by intracellular K+ accumulation/depletion phenomena or by the effects of ACh on time-dependent currents (e.g. the late outward current, ix). Cs+ and Ba2+ block the ACh-induced current. The block produced by 20 mM-Cs+ is instantaneous and increases with hyperpolarization, i.e. it is voltage dependent. The block produced by Ba2+ at high concentrations (greater than 1 mM) is also instantaneous but complete at all potentials studied, and thus voltage independent. At these concentrations, either ion also blocks the background inward rectifier (iK1) current in a similar way. Low [Ba2+] (less than 0.1 mM) cause a block of the ACh-induced current which is instantaneous and little voltage dependent. The block of iK1 in contrast is time and voltage dependent for the same concentrations. These results indicate that the ACh-induced K+ current is different from the background iK1 current.
    [Abstract] [Full Text] [Related] [New Search]