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Updated: Jun 15, 2026

Voltage-Dependent Potassium Current Recording on H9c2 Cardiomyocytes via the Whole-Cell Patch-Clamp Technique
Published on: November 11, 2022
Open channel block of Kv1.5 currents by citalopram
Hyang Mi Lee1, Sang June Hahn, Bok Hee Choi
1Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju, Jeonbuk 561-180, Republic of Korea.
Aim:
To examine whether selective serotonin reuptake inhibitor citalopram interacts with Kv1.5, one of the cardiovascular-specific Kv channel isoforms.
Methods:
The interaction between citalopram and Kv1.5 expressed in Chinese hamster ovary cells was studied using the whole-cell patch-clamp technique.
Results:
Citalopram reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an IC(50) value and a Hill coefficient of 2.8+/-1.1 micromol/L and 0.8+/-0.3, respectively. Citalopram-induced inhibition of Kv1.5 is associated with time-dependent development of block without modifying the kinetics of current activation. The inhibition increased steeply between -30 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to 0 mV, inhibition displayed an additional voltage dependence, consistent with an electrical distance delta of 0.19. Citalopram slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of citalopram, were superimposed. Inhibition of Kv1.5 by citalopram was use-dependent.
Conclusion:
The present results suggest that citalopram acts on Kv1.5 currents as an open-channel blocker, and much caution about arrhythmogenic risk is required when using citalopram in the treatment with depressed patients.
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