hKir2.1 assays
hKir2.1
Cardiac inward rectifier potassium (hKir2.1) channels constitute the IK1 channels which are present in all ventricular and atrial myocytes and are important for stabilizing the resting membrane potential. IK1 channels establish the excitation threshold and modulate the final repolarization phase of the action potential (AP) in cardiomyocytes and thus exert profound effects on cardiac excitability and arrhythmogenesis.
hKir2.1 assays & preclinical safety studies
Kir2.1 encoding IK1 is the predominant isoform in human ventricles, whereas Kir2.1 expression in the atrium is only 25% of that in the ventricle. Upregulation of IK1 has been deemed to be a risk factor for atrial arrhythmogenesis . Increase of IK1 yields APD and ERP shortening, thus theoretically increases the curvature of spiral waves and thereby stabilizes rotors and re-entry arrhythmias.
What is the added value of such a study?
- Threshold concentration of hKir2.1 blockade
- Leading to the determination of the safety range versus efficacious concentration
- You obtain your safety margin
Automated Patch Clamp
Technique
- Up to 6 increasing concentrations of test compound or biologic.
- Experiment conducted at room temperature or at physiological temperature (35°C)
- Human Embryonic Kidney HEK-293 cells
Measured parameters
- Amplitude of the current upon hyperpolarization to –120mV (pA)
- Amplitude of the base current at –80mV (pA)
- Ion current amplitude measurement
- Inhibition of hKir2.1 current amplitude (%)
- IC50 value (at least 4 concentrations required)
Main adventages
- High throughput screening
- Cost effective
- Fast process to delivery results
- Perfect at earliest stages
- Design protocol could be adapted
Manual Patch Clamp
Technique
- Human Embryonic Kidney HEK-293 cells
- Experiment conducted at room temperature or at physiological temperature (35°C)
- Up to 4 increasing cumulative concentrations of test compound
- At least 3 treated cells are recommended
Measured parameters
- Amplitude of the current upon hyperpolarization to –120mV (pA)
- Amplitude of the base current at –80mV (pA)
- Ion current amplitude measurement
- Inhibition of hKir2.1 current amplitude (%)
- IC50 value (at least 4 concentrations required)
Measured parameters
- Technically robust
- Highly informative (more accurate IC50 value)
- Strongly replicable
- Design protocol could be adapted
Stimulation protocol
Typical effects of ML133 on Kir2.1 current recorded from HEK-293 cells.
Reference compounds
Reference CompoundsIC₅₀
ML1334.7 µM
BaCL210.7 µM
