Page 42 - F. Cell biology
P. 42
[F. Cell biology-25]
Carteolol increases hERG current and cardiac action potential
duration
Su-Hyun Jo¹˙*
¹Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon
National University College of Medicine, Chuncheon 200-701, Korea
Carteolol is a non-selective beta blocker used to treat glaucoma. We studied the effects of carteolol on a human
K+ channel, human ether-a-go-go-related gene (hERG), expressed in Xenopus oocytes and on action potential of
guinea pig ventricular myocytes. The hERG encodes the pore-forming subunits of the rapidly-activating delayed
rectifier K+ channel in the heart. Mutations in hERG reduce IKr and cause type 2 long QT syndrome, a disorder that
predisposes individuals to life-threatening arrhythmias. Carteolol increased hERG current amplitude at the end of
the voltage steps and hERG tail currents in a concentration-dependent manner. Carteolol did not change the value
of V1/2 for activation curve of hERG tail current, indicating the drug did not affect activation gating. In guinea pig
ventricular myocytes, carteolol did not change the action potential amplitude and the resting membrane potential,
however, the drug increased the action potential duration (APD₉₀, APD₅₀, APD₂₀), showing that carteolol could
cause arrhythmogenic effects in cardiac function.
