Modulation of HERG potassium channel properties by external pH

We expressed the human eag-related gene (HERG), known to encode for the cardiac potassium channel I-Kr, in Chinese hamster ovary (CHO) cells. This study investigated effects of external pH (pH(o)) on HERG current properties using the whole-cell patch-clamp technique. We observed that current amplitude was decreased and kinetics of activation and deactivation were faster when pH(o) was lowered from 7.4 to 6.0, while activation was accelerated and V-1/2 negatively shifted when pH(o) was changed from 7.4 to 8.0, These effects can be explained by surface charge screening, amino acid group titration and/or changes in ionic atmosphere. We conclude that alterations of HERG channel by pH(o) could have consequences for the onset of arrhythmias during cardiac ischemia.