Thomas D, Hammerling BC, Wimmer AB, Wu K, Ficker E, Kuryshev YA, Scherer D, Kiehn J, Katus HA, Schoels W, Karle CA. Direct block of hERG potassium channels by the protein kinase C inhibitor bisindolylmaleimide I (GF109203X).
Cardiovasc Res 2005;
64:467-76. [PMID:
15537500 DOI:
10.1016/j.cardiores.2004.07.023]
[Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 07/28/2004] [Accepted: 07/28/2004] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE
The human ether-a-go-go-related gene (hERG) encodes the rapid component of the cardiac repolarizing delayed rectifier potassium current, I(Kr). The direct interaction of the commonly used protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIM I) with hERG, KvLQT1/minK, and I(Kr) currents was investigated in this study.
METHODS
hERG and KvLQT1/minK channels were heterologously expressed in Xenopus laevis oocytes, and currents were measured using the two-microelectrode voltage clamp technique. In addition, hERG currents in stably transfected human embryonic kidney (HEK 293) cells, native I(Kr) currents and action potentials in isolated guinea pig ventricular cardiomyocytes were recorded using whole-cell patch clamp electrophysiology.
RESULTS
Bisindolylmaleimide I blocked hERG currents in HEK 293 cells and Xenopus oocytes in a concentration-dependent manner with IC(50) values of 1.0 and 13.2 muM, respectively. hERG channels were primarily blocked in the open state in a frequency-independent manner. Analysis of the voltage-dependence of block revealed a reduction of inhibition at positive membrane potentials. BIM I caused a shift of -20.3 mV in the voltage-dependence of inactivation. The point mutations tyrosine 652 alanine (Y652A) and phenylalanine 656 alanine (F656A) attenuated hERG current blockade, indicating that BIM I binds to a common drug receptor within the pore region. KvLQT1/minK currents were not significantly altered by BIM I. Finally, 1 muM BIM I reduced native I(Kr) currents by 69.2% and lead to action potential prolongation.
CONCLUSION
In summary, PKC-independent effects have to be carefully considered when using BIM I as PKC inhibitor in experimental models involving hERG channels and I(Kr) currents.
Collapse