Rudakova E, Wagner M, Frank M, Volk T (2015)
Publication Type: Journal article
Publication year: 2015
Book Volume: 467
Pages Range: 299-309
Journal Issue: 2
DOI: 10.1007/s00424-014-1521-3
Lipid rafts are cholesterol-enriched microdomains of the cell membrane. Here we investigate the localization of the pore forming K(+)-channel ?-subunit Kv4.2 and the ?-subunit KChIP2, underlying the transient outward K(+) current (I to), in lipid rafts in left ventricular myocytes. Furthermore, we explored the impact of membrane cholesterol depletion (using 20 mM methyl-beta-cyclodextrin (MBCD)) on K(+) outward currents. Cholesterol-saturated MBCD (20 mM) served as control. Myocytes were isolated from the left ventricular free wall of Wistar rats. The Triton X-100 (4 °C) insoluble fraction of whole cell protein was analyzed by sucrose density gradient centrifugation followed by Western blot. Kv4.2 and KChIP2 were partially detected in low-density fractions (lipid rafts). MBCD treatment (5 min) resulted in a shift of Kv4.2 and KChIP2 towards high-density fractions. K(+) currents were assessed by whole-cell patch-clamp. MBCD treatment resulted in a 29 ± 3 % decrease in I to (20.0 ± 1.6pApF(-1) vs. 28.5 ± 2.0pApF(-1), n = 15, p < 0.001, V Pip = 40 mV) within 5 min. Control solution resulted in a significantly smaller reduction in I to (17 ± 3 %, p < 0.001, p < 0.01 compared with MBCD). MBCD induced a 38 ± 9 % increase in the non-inactivating current component (I sus) (10.1 ± 0.6pApF(-1) vs. 7.6 ± 0.4pApF(-1), n = 15, p < 0.001). This effect was absent in control solution. The increase in I sus was not sensitive to 100 ?M 4-aminopyridine or 20 mM tetraethylammonium, making a contribution of Kv1.5 or Kv2.1 unlikely. In conclusion, in rat ventricular cardiomyocytes, a fraction of Kv4.2 and KChIP2 is localized in lipid rafts. Membrane cholesterol depletion results in ~12 % net reduction of I to, a redistribution of the channel proteins Kv4.2 and KChIP2 and an increased delayed rectifier current.
APA:
Rudakova, E., Wagner, M., Frank, M., & Volk, T. (2015). Localization of Kv4.2 and KChIP2 in lipid rafts and modulation of outward K+ currents by membrane cholesterol content in rat left ventricular myocytes. Pflügers Archiv: European Journal of Physiology, 467(2), 299-309. https://doi.org/10.1007/s00424-014-1521-3
MLA:
Rudakova, Elena, et al. "Localization of Kv4.2 and KChIP2 in lipid rafts and modulation of outward K+ currents by membrane cholesterol content in rat left ventricular myocytes." Pflügers Archiv: European Journal of Physiology 467.2 (2015): 299-309.
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