Deprecated: Implicit conversion from float 235.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 235.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 235.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 235.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 235.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534 Cardiovasc+Res 2011 ; 89 (4): 862-9 Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
Structural bases for the different anti-fibrillatory effects of chloroquine and quinidine #MMPMID21233253
Cardiovasc Res 2011[Mar]; 89 (4): 862-9 PMID21233253show ga
AIMS: Chloroquine, an anti-malarial quinoline, is structurally similar to quinidine. Both drugs have been shown to block ion channels. We tested the hypothesis that chloroquine's mode of interaction with the vestibule of the cytoplasmic domain of the inward rectifier potassium channel Kir2.1 makes it a more effective I(K1) blocker and anti-fibrillatory agent than quinidine. METHODS AND RESULTS: We used comparative molecular modelling and ligand docking of the three-dimensional structures of quinidine and chloroquine in the intracellular domain of Kir2.1. Simulations predicted that chloroquine effectively blocks potassium flow by binding at the centre of the ion permeation vestibule of Kir2.1. In contrast, quinidine binds the vestibular side, only partially blocking ion movement. We tested the modelling predictions in Kir2.1-expressing human embryonic kidney (HEK)-293 cells. The half-maximal inhibitory concentration for chloroquine block of I(K1) was 1.2 microM, while that of quinidine was 57 microM. Finally, we used optical mapping of Langendorff-perfused mouse hearts with cardiac-specific Kir2.1 up-regulation to compare the anti-fibrillatory effects of the drugs. In five of six hearts, 10 muM quinidine slowed the frequency but did not terminate the tachyarrhythmia. In five of five hearts, 10 muM chloroquine terminated the arrhythmia, restoring sinus rhythm. CONCLUSION: Quinidine only partially blocks I(K1). Chloroquine binds at the centre of the ion permeation vestibule of Kir2.1, which makes it a more effective I(K1) blocker and anti-fibrillatory agent than quinidine. Integrating the structural biology of drug-ion channel interactions with cellular electrophysiology and optical mapping is an excellent approach to understand the molecular mechanisms of anti-arrhythmic drug action and for drug discovery.
free
free
free
Cardiovasc+Res 2011 ; 89 (4): 862-9
