Human Kv1.5 Stable Cell Line - CHL

Kv1.5 is a voltage-gated K⁺ channel which underlies the ultra-rapidly activating delayed rectifier K⁺ current (Ikur) found in human atrial myocytes. Kv1.5 is also expressed in the human ventricle where it is possible it contributes to the K⁺ current through formation of heteromultimeric K⁺ channels with other Kv-alpha subunits. Inhibition of Kv channels increases atrial refractory period in man – this is clinically valuable for the treatment of patients suffering atrial fibrillation, but undesirable for drugs designed to have inert cardiovascular profiles.

Essen Bioscience and OriGene have co-developed a stable human Kv1.5 expressing cell line in human Chinese Hamster Lung (CHL) cells for various functional screening assays.

Figure 1: In a SYBR green qPCR experiment, specific over-expression of KCN5A was determined using gene specific primers. Data are shown as fold over-expression after normalization against GAPDH.

Figure 2: Current-voltage relationship for hKv1.5 channels stably expressed in CHL cells (A). Representative recordings from CHL-Kv1.5 (B) and CHL-wild type cells (C). Experiments were conducted from a holding potential of -80mV. The depolarising step length was 200ms.

Figure 3: Expression profile: outward K⁺ currents of >0.6 nA were observed in 305 of 310 cells (98%), with a mean amplitude of 2.03 ± 0.85 nA (n=310; mean ± S.D.). The peak current in each cell, evoked from a depolarising pulse to +40 mV, was divided into 0.2 nA bins to create the population histogram.

Figure 4: Summary pharmacology of hKv1.5-CHL cell line. Voltage-clamp recordings were made using repeated gating steps, V_h -80mV, V_step +40mV, 1 Hz, pulse duration 250ms. Control traces in black, test compounds in red. IC₅₀ values were obtained by fitting concentration-response curves to values for inhibition of the 1st and 5th pulse in the train (µM, shown in table). Use-dependent and open channel block can be assessed within this protocol (note blue arrow).