Intracellular Mg2+ depletion depresses the delayed rectifier K+ current in guinea pig ventricular myocytes

The Japanese Journal of Physiology
K HiraharaTsuguhisa Ehara

Abstract

The effects of various [Mg2+]i, particularly low [Mg2+]i, on the delayed rectifier K+ current (IK) were studied in guinea pig ventricular myocytes with the patch clamp technique. The magnitude of IK was evaluated from the amplitude of its tail current elicited on repolarization following the depolarizing steps. The pipette-perfusion technique was also used. The initial variations of IK magnitude were dependent on [Mg2+]i in the internal solutions with which the whole-cell recording was begun. With 0.03 to 1 mM [Mg2+]i, IK was relatively stable after patch rupture, showing a minimal decay with time; with 3 mM [Mg2+]i, IK rapidly declined; with [Mg2+]i, less than 0.01 mM IK transiently increased after patch break, but declined progressively thereafter as the magnitude of IK decreased to about 30% of the initial magnitude in 10 min. The decline of IK at low [Mg2+]i showed the following features. The decline was accompanied little by changes in the voltage-activation relation or by changes in the kinetics of current deactivation. The decline was not related to changes in [Ca2+]i and was also observed in ATP gamma S-loaded, isoprenaline-stimulated cells, in which IK channels were presumed to be persistently phosphorylated. An applic...Continue Reading

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Citations

Jan 23, 2003·Molecular Aspects of Medicine·Pietro Delva
Feb 24, 2001·Critical Care Clinics·M S Agus, Z S Agus
Mar 24, 2009·Journal of Molecular and Cellular Cardiology·Keiko IshiharaSatoshi Matsuoka
Jun 5, 2014·Cardiology in Review·Dhaval KolteWilliam H Frishman
Feb 2, 2020·Hospital Practice·Wisit CheungpasitpornStephen B Erickson
Feb 9, 2002·American Journal of Physiology. Heart and Circulatory Physiology·Kaoru YamaokaIssei Seyama
Sep 27, 2020·Antioxidants·Man Liu, Samuel C Dudley
Jan 26, 2020·BMJ Evidence-based Medicine·Charat ThongprayoonKianoush B Kashani
May 18, 2021·Postgraduate Medicine·Charat ThongprayoonWisit Cheungpasitporn
Nov 25, 2006·Archives of Biochemistry and Biophysics·Kanigula MubagwaRegina Macianskiene

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