Skip to Main content Skip to Navigation
Journal articles

Localization of K(+) channels in the tubules of cardiomyocytes as suggested by the parallel decay of membrane capacitance, IK(1) and IK(ATP) during culture and by delayed IK(1) response to barium.: Inward Rectifier Currents and Cardiac T-tubules

Georges Christé 1, *
* Corresponding author
Abstract : Adult ventricular myocytes lose T-tubules over few days in culture, which causes the loss of about 60% of the cell membrane capacitance (Cm) (Mitcheson et al., 1996). In this study, we have measured, in whole-cell voltage-clamped rabbit right ventricular myocytes at 0, 1, 2 and 3-5 days of culture (nine to 20 myocytes at each age) in a defined Dulbecco's modified Eagle's medium, the value of Cm and the magnitudes of the background inward rectifier current (IK(1)) and of the 2,4-dinitrophenol-induced ATP-sensitive potassium current (IK(ATP)). Cm, IK(1) and IK(ATP) all had decreased significantly by 51, 83 and 88%, respectively after 4 days of culture. Analysis using a single exponential decay function of time gave time constants of, 2.6+/-0.2, 2.2+/-0.5 and 2.4+/-0.4 days, respectively. Linear regressions of IK(1) and IK(ATP) versus Cm had regression coefficients of 0.93 and 0. 98, respectively. These observations are consistent with a strong link of the decay of IK(1) and IK(ATP) currents to that of Cm. Furthermore, the time course of changes in IK(1) when an external blocker (100 microm BaCl(2)) was applied and washed by local perfusion (95% change in 50 ms) agrees with a model including a diffusion time constant of 300 ms. This value is consistent with the known kinetics of diffusion of divalent cations in the T-tubules. Taken together, these results could be explained by the localization of a major part of the IK(1) and IK(ATP) currents of ventricular cardiomyocytes in the T-tubules. As a consequence, transient accumulation of K(+) ions in cardiac T-tubules may take place and modulate excitation-contraction coupling.
Complete list of metadatas

Cited literature [14 references]  Display  Hide  Download

https://www.hal.inserm.fr/inserm-00369897
Contributor : Georges Christé <>
Submitted on : Monday, March 23, 2009 - 2:02:00 AM
Last modification on : Thursday, August 20, 2009 - 11:34:22 AM
Long-term archiving on: : Thursday, June 10, 2010 - 6:08:14 PM

Files

Aut-copy_Christe-G_1999_JMCC_2...
Files produced by the author(s)

Identifiers

Collections

Citation

Georges Christé. Localization of K(+) channels in the tubules of cardiomyocytes as suggested by the parallel decay of membrane capacitance, IK(1) and IK(ATP) during culture and by delayed IK(1) response to barium.: Inward Rectifier Currents and Cardiac T-tubules. Journal of Molecular and Cellular Cardiology, Elsevier, 1999, 31 (12), pp.2207-2213. ⟨10.1006/jmcc.1999.1034⟩. ⟨inserm-00369897⟩

Share

Metrics

Record views

597

Files downloads

665