Biomedical vignette

Abstract

The slow component of delayed rectifier K current (IKs) [6, 12] is unique in its slow activation and deactivation kinetics, and is important during cardiac repolarization particularly when the heart rate is fast. Lai et al. [8] investigated the pharmacological properties of human cardiac IKs expressed in Xenopus oocytes by two-electrode voltage clamp techniques. They show that the expressed IKs is 30 times more sensitive to amiodarone than to other delayed rectifier K channel blockers (quinidine, sotalol and procainamide). Since amiodarone is unique in not having reverse use-dependent effects, the authors attribute the pharmacological property of reverse use dependence to failure to block IKs.