Page 44 - F. Cell biology

[F. Cell biology-26]

Regulation of hERG current and cardiac action potential by

pindolol

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

Pindolol is a beta blocker which is used in the treatment of hypertension and angina pectoris. We studied the
effects of pindolol 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, which has an important role in regulation of action potential
duration of cardiac ventricle, resulting in changes in ECG wave. Pindolol decreased hERG current amplitude at the
end of the voltage steps and hERG tail currents only at 1000 µM, the highest concentration we tested. Pindolol 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, pindolol did not change the resting membrane potential, however, the

drug increased the action potential amplitude, action potential duration (APD₉₀, APD₅₀, APD₂₀), suggesting that
pindolol could affect cardiac electrophysiology, particularly in overdose condition.